An Introduction to Javascript and Functional Programming
An Introduction to Javascript and Functional Programming
I’ve always been about the bottom line. Uninterested in pseudo intellectual concepts, fancy terminology and hype. Instead, I always reach for the tools and technologies that help me ship code as soon as possible. This approach was initially productive — specifically when I was building smaller “proof of concept” applications.
Unfortunately, this approach did not scale. As I progressed as a developer I started feeling the law of diminishing return on my productivity. Setting up a project, and reaching basic functionality was fast. But the real problems started creeping up when my applications started growing in complexity. I found that as a project’s lifecycle advanced I was writing complex code. Code that I had written become harder to reason about. In order to understand it, I had to be extremely concentrated.
I had this itching feeling that a better, cleaner approach to developing software had to exist. I had heard whispers about functional programming, and how it allows developers to write more concise and elegant code. I was unknowingly exposed to functional paradigms and patterns for the first time while working with React and Redux. They both incorporated some of the principles, and I liked them. I read about FP — to my initial dismay I saw its paradigms were based on abstract mathematical concepts and that it was very prevalent in academia. Being that my goal is to ship products as fast as possible, this seemed like a counterintuitive approach to what I was trying to achieve. After 4 years in engineering school, I was pretty set on the opinion that academia only tackled theoretical problems, and was unlikely to ever help me in my day-to-day of building things.
🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔
But FP kept haunting me. Elegant solutions and paradigms were sprinkled online in all my favorite open source projects, blog posts and tutorials. I put my skeptecism aside and started delving into FP.
Although the concepts involve new jargon, and include a steep learning curve, I was amazed and really excited about this “new approach”. This series of articles shares my learning experience, and aims at extracting and summarizing the pearls of FP which enable a cleaner, more concise development experience. I will attempt to build an intuitive understanding of the patterns I discuss and frame the problems and the provided solutions as simply as possible, overstepping unnecessarily complex definitions. Learning FP has a reputation for being a bit daunting, but by breaking down the concepts into smaller bits, we will make the ideas easier to digest.
The main difference in FP in comparison to other programming paradigms is a declarative approach (FP) versus an imperative one. Before we dive into formal definitions, let’s explore the differences by looking at an example.
Imperative
// triple the value of every element in a given array
const triple = (arr) => {
let results = []
for (let i = 0; i < arr.length; i++){
results.push(arr[i] * 3)
}
return results
}
// sum all the elements in a given array
const sum = (arr) => {
let result = 0
for (let i = 0; i < arr.length; i++){
result += arr[i]
}
return result
}
Imperative functions in the wild
Does this code seem evil? It should! What are the similarities between the methods above?
- The main complexity of this code snippet derives from the fact that instead of telling the computer what we want it to do, we are instructing it on how to do it. Code that tells the computer how to operate — ie. go to the array at index i and mutate or swap a value is called imperative code.
- This code isn’t readable (😱😱😱). This is a toy example, but as your program grows and your functionality becomes more sophisticated, using for loops like this creates code that is non trivial, and requires our brain to analyze the inner working of the loop while keeping track of indexes, variables and more. Imperative code increases the cognitive load when reading, and over time makes it easier to faulter in reasoning and logic.
Declarative
Let’s rewrite this snippet of code, but in a declarative manner.
// triple the value of every item in a given array
const triple = (arr) => arr.map((currentItem) => currentItem * 3)// sum all the elements in a given array
const sum = (arr) => arr.reduce((prev, current) => prev + current, 0)
.map? .reduce? What is this black magic?
First off, I promise that given the same input, these two methods produce the same output every single time.
A quick aside on the declarative snippet -
.map()is a method accessible from every array in JS. The .map() method creates a new array with the results of calling a provided function on every element in the calling array.
.reduce() is a method that applies a function against an accumulator and each element in the array (from left to right) to reduce it to a single value.
Don’t fret about these just yet. We’re going to explore these handy array-native methods in depths in upcoming posts. But it is clear that the declarative snippet is more concise than the imperative one. It’s also a lot easier to read. Instead of instructing the program on which indexes I want it to access etc, I am simply supplying an expression to .map() and** .reduce()** (an anonymous function in our case) which tells the program what I want it do to every element in the array.
This declarative approach is going to serve us well across the board by:
- Learning and using patterns in your code that are well-known, understandable, and proven to keep away the mistakes that make code harder to understand.
2. Composing shorter, expressive and concise code. After all, the less code we write the less we have to debug.
Most importantly, these tools and paradigms are going to help us achieve our (my) ultimate goal of shipping products faster. Check out the next post, where we discuss functions in JS, why they are special and how their characteristics enable functional programming.
Welcome to the Upside Down
Before we get started, there’s something you need to know … If you’ve ever programmed in JS you’ve probably used FP patterns before! These patterns and paradigms have been there all along, we just haven’t been able to see them properly. We are going to start from the familiar and explore new territory. Things may get a bit … well … strange. But fear not! Together we will survive!
First Class Functions
In Javascript, functions are first class objects. Like I mentioned earlier, we don’t like cryptic terminology, so let’s explain. According to the Mozilla developer glossary:
A programming language is said to have First-class functions when functions in that language are treated like any other variable. For example, in such a language, a function can be passed as an argument to other functions, can be returned by another function and can be assigned as a value to a variable.
Functions as constants
In the following example we will declare a const and assign it an anonymous arrow functions.
After the initial assignment constFunction is a constant with a value of a function. We verify that by logging the constFunction variable in the Chrome inspector. Because constFunction is a function we can also invoke it.
Functions as values of keys of an object
Now that we understand that variables can hold functions, let’s demonstrate a function as a value of a key in an object. This should be familiar for anyone who has done any object oriented programming before.
const functionAsObjectProperty = {
print: (value) => console.log(value)
};
functionAsObjectProperty.print("mic check"); // "mic check"
Functions as array items
When functions are first class objects we can pass them as data to an array, just like any other data type. Let’s use the Chrome console and check this out.
Higher order functions
Now that we’ve warmed up, let’s get to the interesting stuff :) JS developers see functions that accept other functions as arguments on a daily basis. If you’re coming from a language that doesn’t support FP this should seem a bit weird 😳😳😳😳😳😳😳 Let’s acquaint ourselves with this concept by looking at some examples.
An asynchronous function that accepts a callback function.
const jsonfile = require('jsonfile')
const file = '/tmp/data.json'
const obj = {name: 'JP'}
const errorLoggerFunction = (err) => console.error(err);
jsonfile.writeFile(file, obj, errorLoggerFunction)
errorLoggerFunction is defined as a function with the ES6 arrow syntax
We’re using the jsonfile npm module in this example for the _writeFile m_ethod. The third parameter that writeFile is expecting is a function. When the jsonfile.writeFile method executes it will either succeed or fail. If it fails it will execute the errorLoggerFunction. Alternatively, we could have gone for a more terse syntax, and dropped the named function:
const jsonfile = require('jsonfile')
const file = '/tmp/data.json'
const obj = {name: 'JP'}
jsonfile.writeFile(file, obj, (err) => console.error(err))
It’s an anonymous function because we didn’t name it
setTimeout
const timeout = () => {
setTimeout(() => alert("WoW"), 1000);
}
Classic callback example
This example shows the built in asynchronous setTimeout method which accepts 2 arguments. Let’s formalize this a little bit and explain the setTimeout function in functional programming terms.
Let’s start by reading the signature of the function. We can observe that the number of arguments that setTimeout takes is two. In functional programming the number of arguments a function takes is called its Arity, from words like unary, binary, ternary etc. So we can say that setTimeout is of arity 2, or equivalently say that is a binary function.
The arguments that setTimeout expects is a function and a time interval to wait before executing the given function. Hmmm … another function that accepts a function as input?
In functional programming this is so common that these types of functions even have a name! They are called higher order functions.
A higher order function is a function that takes a function as an argument, or returns a function.
There you go. Now you can drop this term low key in any random conversation at work / with friends and sound like a boss! 😂😂😂
const add = (x,y) => x + y;
const subtract = (x,y) => x - y;
const multiply = (x,y) => x * y;const arrayOfFunctions = [add, subtract, multiply];
arrayOfFunctions.forEach(calculationFunction => console.log(calculationFunction(1,1))); // 2 0 1
On line 5 we are declaring an array of functions. We are then using the forEach method to iterate over the array. forEach is a natively supported ES6+ function, that accepts a function to execute on every item in the array. Therefore, forEach is also a higher order function!
Our forEach accepts an anonymous function as input. forEach will iterate over the array and implicitly access the current item in the array and call it getCalculation. It is worth noting that forEach implicitly accesses array elements, in comparison to how we would have accessed the current element if we had used a regular for loop — ie. arrayOfFunctions[i]. Every item in our array is a function, therefore we invoke getCalculation with the arguments that it is expecting.
Fantastic. This example illustrates that functions in functional programming can be passed into arrays (lists) just like any other data type. Functions can go anywhere!
Now let’s build our own higher order function!
const addWrapper = () => (x,y) => x + y;const add = addWrapper();
const sum1 = add (1,2); // 3
// Or we could do it like this
const sum2 = addWrapper()(4,4); // 8
view raw
functionThatReturnsFunction.js hosted with ❤ by GitHub
The addWrapper function returns a simple addition function when called. By invoking the result of the addWrapper function and supplying it two arguments, we have access to the anonymous addition function.
We could get even crazier with our level of indirection and write a function that returns a function, that in turn returns its own function!
const bankStatement =
name =>
location =>
balance =>
Hello ${name}! Welcome to the bank of ${location}. Your current balance is ${balance};const statementExpectingLocation = bankStatement("Omer");
const statementExpectingBalance = statementExpectingLocation("NYC");
const bankStatementMsg = statementExpectingBalance("100 million"); // wishful thinking?console.log(bankStatementMsg); // Hello Omer! Welcome to the bank of NYC. Your current balance is 100 million
// We could also call the function with all the arguments up front
const msg = bankStatement("Jeff Bezos")("Silicon Valley")("97.7 billion");
console.log(msg); // Hello Jeff Bezos! Welcome to the bank of Silicon Valley. Your current balance is 97.7 billion
I hope you like curry!
This is a very powerful pattern in functional programming. We will explore it in depth in the coming posts when we talk about currying and partial applications.
First class functions are the cornerstones of any functional programming language. The main point that you should take away from our discussion about first class functions is that functions can be assigned as constants, variables, placed as array elements and even set as values of keys on an object. Additionally, (and most importantly ?!) functions can be returned to and from functions —** just like any other data type!**
Motivation
So many of our bugs are rooted in IO related, data mutation, side effect bearing code. These creep up all over our code base — from things like accepting user inputs, receiving an unexpected response via an http call, or writing to the file system. Unfortunately, this is a harsh reality that we should grow accustomed to dealing with. Or is it?
What if I told you, that we could minimize the parts of our code which executed the critical / volatile bits of our program? We could enforce (by convention) that the large majority of our code base would be pure, and limit IO related / side effect bearing code to a specific part of our codebase. This would make our debugging process a lot easier, more coherent and easier to reason about.
So, what is this mythical pure function? A pure function has two main characteristics:
1. A pure function is deterministic. This means, that given the same input, the function will always return the same output. To illustrate this as a function in mathematical terms (this will be quick!) it is a well defined function. Every input returns a single output, every single time.
A pure function
const add = (x, y) => x + y // A pure function
add is a pure function because it’s output is solely dependent on the arguments it receives. Therefore, given the same values, it will always produce the same output.
How about this one?
const magicLetter = '*'
const createMagicPhrase = (phrase) =>${magicLetter}abra${phrase}
Something about this one is fishy…. The createMagicPhrase function is dependent on a value which is external to its scope. Therefore, it is not pure!
An impure function
const fetchLoginToken = externalAPI.getUserToken
Is fetchLoginToken a pure function? Does it return the same value every single time? Absolutely not! Sometimes it will work — sometimes the server will be down and we will get a 500 error — and at some point in the future the API may change so that this call is no longer valid! So, because the function is non-deterministic, we can safely say that it is an impure function.
2. A pure function will not cause side effects. A side effect is any change in the system that is observable to the outside world.
const calculateBill = (sumOfCart, tax) => sumOfCart * tax
Is calculateBill pure? Definitely :) It exhibits the two necessary characteristics:
- The function depends only on its arguments to produce a result
- The function does not cause any side effects
The Mostly Adequate Guide states that side effects include, but are not limited to:
- changing the file system
- inserting a record into a database
- making an http call
- mutations
- printing to the screen / logging
- obtaining user input
- querying the DOM
- accessing system state
Why should our functions be pure?
Readability -> Side effects make our code harder to read. Since a non pure function is not deterministic it may return several different values for a given input. We end up writing code that needs to account for the different possibilities. Let’s look at another http based example:
async function getUserToken(id) {
const token = await getTokenFromServer(id);
return token;
}
This snippet can fail in so many different ways. What if the id passed to the getTokenFromServer was invalid? What if the server crashed and returned an error, instead of the expected token? There are a lot of contingencies that need to be planned for, and forgetting one (or several!) of them is very easy.
Additionally, a pure function is easier to read, as it requires no context. It receives all of its needed parameters up front, and does not talk / tamper with the state of the application.
Testability -> Because pure functions are deterministic by nature, writing unit tests for them is a lot simpler. Either your function works or it doesn’t 😁
Parallel Code -> Since pure functions only depend on their input, and will not cause side effects, they are great for scenarios where parallel threads run and use shared memory.
Modularity and Reusability -> Think of pure functions as little units of logic. Because they only depend on the input you feed them, you can easily reuse functions between different parts of your codebase or different projects altogether.
Referential Transparency -> This one sounds so complicated 🙄🙄 When I first read the title I wanted a coffee break! Simply put, referential transparency means that a function call could be replaced by its output value, without changing the overall behavior of our program. This is mostly useful as a framework of thought when creating pure functions.
It’s pure and all…. but does it do anything?
It’s important to note that although pure functions offer a ton of benefits, it’s not realistic to only have pure functions in our applications. After all, if we did our application would have no side effects, thus not produce any observable effects to the outside world. That would be pretty boring 😥😥😥. Instead we will try to encapsulate all of our side effects to specific parts of our codebase. That way, assuming we have written unit tests for our pure functions and know they are working, if something breaks in our app, it will be a lot easier to track down.
Let’s get pure
Let’s conclude our discussion by converting the following non pure function to pure. This is a contrived example, but demonstrates how we can easily refactor unpure code to pure.
let a = 4;
let b = 5;
let c = 6;
const updateTwoVars = (a) => {
b++;
c = a * b;
}updateTwoVars(a);
console.log(b,c); // b = 6, c = 24
Let’s start by reviewing why this function is unpure. Our function is unpure because it depends on a and b, which are external to its scope. In addition, it is also directly mutating (changing) the values of the variables. The quickest way to refactor this function is
- First ensure that all the variables that the function depends on are passed as arguments
- Instead of mutating (manipulating) b and c, we can return new values which will reflect the new values.
let a = 4;
let b = 5;
let c = 6;
const updateTwoVars = (a, b, c) => [b++, a * b];const updateRes = updateTwoVars(a,b,c);
b = updateRes[0]
c = updateRes[1]
Summary
We’ve covered a lot of the benefits of transitioning our code base to include more pure functions. It makes our code easier to reason about, test, and most importantly more predictable. Remember, pure functions are not about completely ridding our code base of side effects. It’s about constraining them to a definitive location and eliminating as much of them as possible. This approach will justify itself many times over, when your programs start growing in size and complexity.
Currying is when we call a function with fewer arguments than it expects. In turn, the invoked function returns a function that takes the remaining arguments.
const magicPhrase =
(magicWord) =>
(muggleWord) =>
magicWord + muggleWord
We could then invoke this function with the following pattern
Call it maaagic
Writing functions that return functions, that in turn return some output (possibly another function!) can get quite cumbersome. Luckily we have functional JS helper libraries like Ramda and lodash which provide us with utility methods such as curry. The curry utility wraps normally declared functions and transforms them into a series of one-argument functions. So we could convert the previous code to:
import _ from "lodash"const magicPhrase = _.curry((magicWord, muggleWord) => magicWord + muggleWord)
const muggleWordAccepter = magicPhrase("Abra kedabra ")
muggleWordAccepter("dishwasher")
Another example would be a revamped implementation of our favorite add function
import _ from "lodash"const addFunction = _.curry((a, b) => a + b)
const addOne = add(1)
addTen(1)
So we are essentially, “pre loading” the add function with the first variable. Our function has the ability to remember the first value passed thanks to JS closure.
Why You Should Care About Currying
- Currying gives us the ability to compose terse, concise and reusable functions.
2. We use these functions as clean, testable units of logic to compose the more logically complex parts of our programs.
3. With currying, any function that works on single elements can be converted into a function that works on arrays (lists), simply by wrapping it with map.
const getObjectId = (obj) => obj.id // works on single objectconst arrayOfObjects = [{id: 1}, {id: 2}, {id: 3}, {id: 4}]
const arrayOfIDs = arrayOfObjects.map(getObjectId)
BAM! Our function that worked on single elements can work on arrays!
Examples
The only real way to get familiar with these concepts is to practice :) Let’s get to it. We shall start with one more example of converting a function that operates on a single element to a function that operates on an array.
const getFirstTwoLettersOfWord = (word) => word.substring(0,2)// We can convert it, by wrapping it in the map method
["aabb", "bbcc", "ccdd", "ddee"].map(getFirstTwoLettersOfWord)
The next example comes out of the amazing Mostly Adequate guide, with a small ES6 refactors :)
Let’s refactor the max function so that it won’t reference any arguments.
arr = [2,4,6,8,9]// LEAVE BE:
const getMax = (x, y) => {
return x >= y ? x : y;
};// REFACTOR THIS ONE:
const max = (arr) => {
return arr.reduce((acc, x) => {
return getMax(acc, x);
}, -Infinity);
};const max = arr.reduce(getMax, -Infinity)
Let’s wrap the native JS slice method so that it functional and curried.
import _ from "lodash"const arr = ["barney", "fred", "dave"]
arr.slice(0, 2) // ["barney", "fred"]
const slice = _.curry((start, end, arr) => arr.slice(start, end));
const sliceWithSetIndexes = slice(0,2)sliceWithSetIndexes(arr) // ["barney", "fred"]
Summary
We’ve seen several examples where we curry JS functions. Currying refers to the process of transforming a function with multiple arity (arguments accepted) into the same function with less arity. It utilizes JS closure to remember the arguments used in the previous invocations. Currying twists functions around so that they can work more naturally together. Its biggest advantage is that it easily allows for function composition, which we will explore in depth in the next post!
Learn More
☞ 10 JavaScript array methods you should know
☞ Introducing TensorFlow.js: Machine Learning in Javascript
☞ Machine Learning in JavaScript with TensorFlow.js
☞ 5 ways to build real-time apps with JavaScript
☞ Full Stack Developers: Everything You Need to Know
☞ 5 Javascript (ES6+) features that you should be using in 2019
☞ The Complete JavaScript Course 2019: Build Real Projects!
☞ JavaScript: Understanding the Weird Parts
☞ Vue JS 2 - The Complete Guide (incl. Vue Router & Vuex)
☞ The Full JavaScript & ES6 Tutorial - (including ES7 & React)
Originally published by Omer Goldberg at https://hackernoon.com
Introduction New Features in TypeScript 3.7 and How to Use Them
The TypeScript 3.7 release is coming soon, and it's going to be a big one.
The target release date is November 5th, and there are some seriously exciting headline features included:
- Assert signatures.
- Recursive type aliases.
- Top-level await.
- Null coalescing.
- Optional chaining.
Personally, I'm super excited about this, they're going to whisk away all sorts of annoyances that I've been fighting in TypeScript while building HTTP Toolkit.
If you haven't been paying close attention to the TypeScript development process though, it's probably not clear what half of these mean, or why you should care. Let's talk through all of them.
Assert SignaturesThis is a brand-new and little-known TypeScript feature, which allows you to write functions that act like type guards as a side-effect, rather than explicitly returning their boolean result.
It's easiest to demonstrate this with a JavaScript example:
function assertString(input) {
if (typeof input === 'string')
return;
else
throw new Error('Input must be a string!');
}
function doSomething(input) {
assertString(input);
// ... Use input, confident that it's a string
}
doSomething('abc');
// All good doSomething(123); // Throws an error
This pattern is neat and useful, and you can't use it in TypeScript today.
TypeScript can't know that you've guaranteed the type of input after it's run assertString. Typically, people just make the argument input: string to avoid this, and that's good. But, it also just pushes the type checking problem somewhere else, and in cases where you just want to fail hard, it's useful to have this option available.
Fortunately, soon we will:
// With TS 3.7
function assertString(input: any):
asserts input is string {
// <-- the magic
if (typeof input === 'string')
return;
else
throw new Error('Input must be a string!');
}
function doSomething(input: string | number) {
assertString(input);
// input's type is just 'string' here }
Here assert input is string means that if this function ever returns, TypeScript can narrow the type of input to string, just as if it was inside an if block with a type guard.
To make this safe, that means if the assert statement isn't true then your assert function must either throw an error or not return at all (kill the process, infinite loop, you name it).
That's the basics, but this actually lets you pull some really neat tricks:
// With TS 3.7
// Asserts that input is truthy, throwing immediately if not:
function assert(input: any):
asserts input { // <-- not a typo
if (!input)
throw new Error('Not a truthy value');
}
declare const x: number | string | undefined;
assert(x); // Narrows x to number | string
// Also usable with type guarding expressions!
assert(typeof x === 'string');
// Narrows x to string // -- Or use assert in your tests: --
const a: Result | Error = doSomethingTestable();
expect(a).is.instanceOf(result);
// 'instanceOf' could 'asserts a is Result'
expect(a.resultValue).to.equal(123);
// a.resultValue is now legal // -- Use as a safer ! that throws immediately if
// you're wrong --
function assertDefined<T>(obj: T):
asserts obj is NonNullable<T> {
if (obj === undefined || obj === null) {
throw new Error('Must not be a nullable value');
}
}
declare const x: string | undefined;
// Gives y just 'string' as a type, could throw elsewhere later:
const y = x!;
// Gives y 'string' as a type, or throws immediately if you're wrong:
assertDefined(x); const z = x;
// -- Or even update types to track a function's side-effects --
type X<T extends string | {}> = { value: T };
// Use asserts to narrow types according to side effects:
function setX<T extends string | {}>(x: X<any>, v: T):
asserts x is X<T> {
x.value = v;
}
declare let x: X<any>;
// x is now { value: any };
setX(x, 123);
// x is now { value: number };
This is still in flux, so don't take it as the definite result, and keep an eye on the pull request if you want the final details.
There's even a discussion there about allowing functions to assert something and return a type, which would let you extend the final example above to track a much wider variety of side effects, but we'll have to wait and see how that plays out.
Top-Level AwaitAsync/await is amazing and makes promises dramatically cleaner to use.
Unfortunately, though, you can't use them at the top level. This might not be something you care about much in a TS library or application, but if you're writing a runnable script or using TypeScript in a REPL, then this gets super annoying.
It's even worse if you're used to frontend development, since top-level await has been working nicely in the Chrome and Firefox console for a couple of years now.
Fortunately though, a fix is coming. This is actually a general stage-3 JS proposal, so it'll be everywhere else eventually too, but for TS devs 3.7 is where the magic happens.
This one's simple, but let's have another quick demo anyway:
// Your only solution right now for a script that does something async:
async function doEverything() {
...
const response = await fetch('http://example.com');
...
}
doEverything(); // <- eugh (could use an IIFE instead, but even more eugh)
With top-level await:
// With TS 3.7:
// Your script: ...
const response = await fetch('http://example.com');
// ...
There's a notable gotcha here: if you're not writing a script, or using a REPL, don't write this at the top level, unless you really know what you're doing!
It's totally possible to use this to write modules that do blocking async steps when imported. That can be useful for some niche cases, but people tend to assume that their import statement is a synchronous, reliable, and fairly quick operation, and you could easily hose your codebase's startup time if you start blocking imports for complex async processes (even worse, processes that can fail).
This is somewhat mitigated by the semantics of imports of async modules: they're imported and run in parallel, so the importing module effectively waits for Promise.all(importedModules) before being executed.
Rich Harris wrote an excellent piece on a previous version of this spec before that change when imports ran sequentially and this problem was much worse), which makes for good background reading on the risks here if you're interested.
It's also worth noting that this is only useful for module systems that support asynchronous imports. There isn't yet a formal spec for how TS will handle this, but that likely means that a very recent target configuration, and, either ES Modules or Webpack v5 (whose alphas have experimental support), will be used at runtime.
Recursive Type AliasesIf you're ever tried to define a recursive type in TypeScript, you may have run into StackOverflow questions like this: https://stackoverflow.com/questions/47842266/recursive-types-in-typescript.
Right now, you can't. Interfaces can be recursive, but there are limitations to their expressiveness, and type aliases can't. That means right now, you need to combine the two: define a type alias and extract the recursive parts of the type into interfaces. It works, but it's messy, and we can do better.
As a concrete example, this is the suggested type definition for JSON data:
type JSONValue = | string | number | boolean | JSONObject | JSONArray;
interface JSONObject { [x: string]: JSONValue; }
interface JSONArray extends Array<JSONValue> { }
That works, but the extra interfaces are only there because they're required to get around the recursion limitation.
Fixing this requires no new syntax; it just removes that restriction, so the below compiles:
// With TS 3.7:
type JSONValue = | string | number | boolean | { [x: string]: JSONValue } | Array<JSONValue>;
Right now, that fails to compile with Type alias 'JSONValue' circularly references itself. Soon though, soon...
Null CoalescingAside from being difficult to spell, this one is quite simple and easy. It's based on a JavaScript stage-3 proposal, which means it'll also be coming to your favorite vanilla JavaScript environment soon (if it hasn't already).
In JavaScript, there's a common pattern for handling default values, and falling back to the first valid result of a defined group. It looks something like this:
// Use the first of firstResult/secondResult which is truthy:
const result = firstResult || secondResult;
// Use configValue from provided options if truthy, or 'default' if not:
this.configValue = options.configValue || 'default';
This is useful in a host of cases, but due to some interesting quirks in JavaScript, it can catch you out. If firstResult or options.configValue can meaningfully be set to false, an empty string or 0, then this code has a bug. If those values are set, then when considered as booleans they're falsy, so the fallback value (secondResult / 'default') is used anyway.
Null coalescing fixes this. Instead of the above, you'll be able to write:
// With TS 3.7:
// Use the first of firstResult/secondResult which is *defined*:
const result = firstResult ?? secondResult;
// Use configSetting from provided options if *defined*, or 'default' if not:
this.configValue = options.configValue ?? 'default';
?? differs from || in that it falls through to the next value only if the first argument is null or undefined, not falsy. That fixes our bug. If you pass false as firstResult, that will be used instead of secondResult because, while it's falsy, it is still defined, and that's all that's required.
It's simple but super-useful, as it takes away a whole class of bugs.
Optional ChainingLast but not least, optional chaining is another stage-3 proposal that is making its way into TypeScript.
This is designed to solve an issue faced by developers in every language: how do you get data out of a data structure when some or all of it might not be present?
Right now, you might do something like this:
// To get data.key1.key2, if any level could be null/undefined:
let result = data ? (data.key1 ? data.key1.key2 : undefined) : undefined;
// Another equivalent alternative:
let result = ((data || {}).key1 || {}).key2;
Nasty! This gets much much worse if you need to go deeper, and although the second example works at runtime, it won't even compile in TypeScript, since the first step could be {}, in which case key1 isn't a valid key at all.
This gets still more complicated if you're trying to get into an array, or there's a function call somewhere in this process.
There's a host of other approaches to this, but they're all noisy, messy & error-prone. With optional chaining, you can do this:
// With TS 3.7:
// Returns the value is it's all defined & non-null, or undefined if not.
let result = data?.key1?.key2;
// The same, through an array index or property, if possible:
array?.[0]?.['key'];
// Call a method, but only if it's defined:
obj.method?.();
// Get a property, or return 'default' if any step is not defined:
let result = data?.key1?.key2 ?? 'default';
The last case shows how neatly some of these dovetails together: null coalescing + optional chaining is a match made in heaven.
One gotcha: this will return undefined for missing values, even if they were null, e.g. in cases like (null)?.key (returns undefined). A small point, but one to watch out for if you have a lot of null in your data structures.
That's the lot! That should outline all the essentials for these features, but there are lots of smaller improvements, fixes, and editor support improvements coming too, so take a look at the official roadmap if you want to get into the nitty-gritty.
Angular 8 Pagination Example and Tutorial
Pagination is the best way to show huge number of records in series for any application. Also showing/fetching thousands of record at one go will affect the performance of the application.
Pagination is the best way to show huge number of records in series for any application. Also showing/fetching thousands of record at one go will affect the performance of the application.
For example, when you search something that returns a large number of records which cannot be shown on a single web page therefore, those records are part into number of pages that can be accessed through links via pagination structure.
So today in this demo we will discuss the simple pagination in Angular 8.
Step 1: Create a basic app with angular cling new angular8-simple-pagination-example
By typing the above command we will see a basic angular app created on the current folder. So move to the created folder by typing **cd angular8-simple-pagination-example/. **You can check the newly created app by typing http://localhost:4200 on the browser.
Step 2: install ngx-pagination pagination dependency from terminalSo run the below command over terminal
npm install ngx-pagination --save
Step 3: Create dummy records for pagination
Now we will create static data to show the pagination. So lets have a look on the code under file **app.component.ts **
import { Component } from '@angular/core';
import {NgxPaginationModule} from 'ngx-pagination';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = 'simple pagination demo';
collection = [];
constructor(){
for(let i=1;i<=100;i++){
let Obj = {'name': `Employee Name ${i}`,'code': `EMP00 ${i}`}
this.collection.push(Obj);
}
}
}
In the above file, we can see that inside constructor we have created a loop for created dummy record for 100 employees having employee name & code for showing pagination.
Step 4: Import dependency in app.module.tsNow let's have a look on the code inside **app.module.ts **where the ngx-pagination module has been imported
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { NgxPaginationModule } from 'ngx-pagination';
import { AppComponent } from './app.component';
@NgModule({
declarations: [
AppComponent
],
imports: [
BrowserModule,
NgxPaginationModule
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }
Now one last step needed to do is, add the below code anywhere inside app.component.html
* Emp Name | Emp code
{{item.name}} | {{item.code}}
Now, we are done with all the needed steps for the pagination in our angular application.
Step 6: Run the app
Run the app over the terminal with npm start and check the app after typing the url http://localhost:4200/.** **A page will open like below:
By following these easy steps we can easily achieve the client side pagination in Angular 8 application. If you want to impliment server side pagination in angular8 Server Side Pagination in Angular Example and Tutorial . You can also find other demos of Angular Sample Application here to start working on enterprise level application. Click here to view more about the pagination package over npm.
Create Simple Login Page using Angular 8 and HTTP Authentication
In this article, you'll learn how to setup a simple login page using Angular 8 and Basic HTTP authentication
In this article, you'll learn how to setup a simple login page using Angular 8 and Basic HTTP authentication
Tutorial built with Angular 8.0.2 and the Angular CLI
Angular CLI was used to generate the base project structure with the ng new command, the CLI is also used to build and serve the application. For more info about the Angular CLI see https://angular.io/cli.
Styling of the example app is all done with Bootstrap 4.3, for more info about Bootstrap see https://getbootstrap.com/docs/4.3/getting-started/introduction/.
Running the Angular 8 Basic Authentication Tutorial Example Locally- Install NodeJS and NPM from https://nodejs.org/en/download/.
- Download or clone the tutorial project source code from https://github.com/cornflourblue/angular-8-basic-authentication-example
- Install all required npm packages by running
npm installfrom the command line in the project root folder (where the package.json is located). - Start the application by running
npm startfrom the - command line in the project root folder, this will build the application
- and automatically launch it in the browser on the URL
- http://localhost:4200.
NOTE: You can also run the app directly using the Angular CLI command ng serve --open. To do this first install the Angular CLI globally on your system with the command npm install -g @angular/cli.
The Angular 8 basic authentication example app uses a fake / mock backend by default so it can run in the browser without a real api, to switch to a real backend api you just have to remove or comment out the line below the comment // provider used to create fake backend located in the /src/app/app.module.ts file.
The app and code structure of the tutorial mostly follows the best practice recommendations in the official Angular Style Guide, with a few of my own tweaks here and there.
Each feature has it's own folder (home & login), other shared/common code such as services, models, helpers etc are placed in folders prefixed with an underscore _ to easily differentiate them and group them together at the top of the folder structure.
The index.ts files in each folder are barrel files that group the exported modules from a folder together so they can be imported using the folder path instead of the full module path and to enable importing multiple modules in a single import (e.g. import { AuthenticationService, UserService } from '../_services').
Path aliases @app and @environments have been configured in tsconfig.json that map to the /src/app and /src/environments directories. This allows imports to be relative to the app and environments folders by prefixing import paths with aliases instead of having to use long relative paths (e.g. import MyComponent from '../../../MyComponent').
Here are the main project files that contain the application logic, I left out some files that were generated by Angular CLI ng new command that I didn't change.
- src
- app
- _helpers
- auth.guard.ts
- basic-auth.interceptor.ts
- error.interceptor.ts
- fake-backend.ts
- index.ts
- _models
- user.ts
- index.ts
- _services
- authentication.service.ts
- user.service.ts
- index.ts
- home
- home.component.html
- home.component.ts
- index.ts
- login
- login.component.html
- login.component.ts
- index.ts
- app.component.html
- app.component.ts
- app.module.ts
- app.routing.ts
- environments
- environment.prod.ts
- environment.ts
- index.html
- main.ts
- polyfills.ts
- styles.less
- package.json
- tsconfig.json
Path: /src/app/_helpers/auth.guard.ts
The auth guard is an angular route guard that's used to prevent unauthenticated users from accessing restricted routes, it does this by implementing the CanActivate interface which allows the guard to decide if a route can be activated with the canActivate() method. If the method returns true the route is activated (allowed to proceed), otherwise if the method returns false the route is blocked.
The auth guard uses the authentication service to check if the user is logged in, if they are logged in it returns true from the canActivate() method, otherwise it returns false and redirects the user to the login page.
Angular route guards are attached to routes in the router config, this auth guard is used in app.routing.ts to protect the home page route.
import { Injectable } from '@angular/core';
import { Router, CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot } from '@angular/router';
import { AuthenticationService } from '@app/_services';
@Injectable({ providedIn: 'root' })
export class AuthGuard implements CanActivate {
constructor(
private router: Router,
private authenticationService: AuthenticationService
) { }
canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
const currentUser = this.authenticationService.currentUserValue;
if (currentUser) {
// logged in so return true
return true;
}
// not logged in so redirect to login page with the return url
this.router.navigate(['/login'], { queryParams: { returnUrl: state.url } });
return false;
}
}
Path: /src/app/_helpers/basic-auth.interceptor.ts
The Basic Authentication Interceptor intercepts http requests from the application to add basic authentication credentials to the Authorization header if the user is logged in.
It's implemented using the HttpInterceptor class included in the HttpClientModule, by extending the HttpInterceptor class you can create a custom interceptor to modify http requests before they get sent to the server.
Http interceptors are added to the request pipeline in the providers section of the _app.module.ts_ file.
import { Injectable } from '@angular/core';
import { HttpRequest, HttpHandler, HttpEvent, HttpInterceptor } from '@angular/common/http';
import { Observable } from 'rxjs';
import { AuthenticationService } from '@app/_services';
@Injectable()
export class BasicAuthInterceptor implements HttpInterceptor {
constructor(private authenticationService: AuthenticationService) { }
intercept(request: HttpRequest, next: HttpHandler): Observable> {
// add authorization header with basic auth credentials if available
const currentUser = this.authenticationService.currentUserValue;
if (currentUser && currentUser.authdata) {
request = request.clone({
setHeaders: {
Authorization: `Basic ${currentUser.authdata}`
}
});
}
return next.handle(request);
}
}
Path: /src/app/_helpers/error.interceptor.ts
The Error Interceptor intercepts http responses from the api to check if there were any errors. If there is a 401 Unauthorized response the user is automatically logged out of the application, all other errors are re-thrown up to the calling service so an alert with the error can be displayed on the screen.
It's implemented using the HttpInterceptor class included in the HttpClientModule, by extending the HttpInterceptor class you can create a custom interceptor to catch all error responses from the server in a single location.
Http interceptors are added to the request pipeline in the providers section of the app.module.ts file.
import { Injectable } from '@angular/core';
import { HttpRequest, HttpHandler, HttpEvent, HttpInterceptor } from '@angular/common/http';
import { Observable, throwError } from 'rxjs';
import { catchError } from 'rxjs/operators';
import { AuthenticationService } from '@app/_services';
@Injectable()
export class ErrorInterceptor implements HttpInterceptor {
constructor(private authenticationService: AuthenticationService) { }
intercept(request: HttpRequest, next: HttpHandler): Observable> {
return next.handle(request).pipe(catchError(err => {
if (err.status === 401) {
// auto logout if 401 response returned from api
this.authenticationService.logout();
location.reload(true);
}
const error = err.error.message || err.statusText;
return throwError(error);
}))
}
}
Path: /src/app/_helpers/fake-backend.ts
In order to run and test the Angular application without a real backend API, the example uses a fake backend that intercepts the HTTP requests from the Angular app and send back "fake" responses. This is done by a class that implements the Angular HttpInterceptor interface, for more information on Angular HTTP Interceptors see https://angular.io/api/common/http/HttpInterceptor
The fake backend contains a handleRoute function that checks if the request matches one of the faked routes in the switch statement, at the moment this includes POST requests to the /users/authenticate route for handling authentication, and GET requests to the /users route for getting all users.
Requests to the authenticate route are handled by the authenticate() function which checks the username and password against an array of hardcoded users. If the username and password are correct then an ok response is returned with the user details, otherwise an error response is returned.
Requests to the get users route are handled by the getUsers() function which checks if the user is logged in by calling the new isLoggedIn() helper function. If the user is logged in an ok() response with the whole users array is returned, otherwise a 401 Unauthorized response is returned by calling the new unauthorized() helper function.
If the request doesn't match any of the faked routes it is passed through as a real HTTP request to the backend API.
import { Injectable } from '@angular/core';
import { HttpRequest, HttpResponse, HttpHandler, HttpEvent, HttpInterceptor, HTTP_INTERCEPTORS } from '@angular/common/http';
import { Observable, of, throwError } from 'rxjs';
import { delay, mergeMap, materialize, dematerialize } from 'rxjs/operators';
import { User } from '@app/_models';
const users: User[] = [{ id: 1, username: 'test', password: 'test', firstName: 'Test', lastName: 'User' }];
@Injectable()
export class FakeBackendInterceptor implements HttpInterceptor {
intercept(request: HttpRequest, next: HttpHandler): Observable> {
const { url, method, headers, body } = request;
// wrap in delayed observable to simulate server api call
return of(null)
.pipe(mergeMap(handleRoute))
.pipe(materialize()) // call materialize and dematerialize to ensure delay even if an error is thrown (https://github.com/Reactive-Extensions/RxJS/issues/648)
.pipe(delay(500))
.pipe(dematerialize());
function handleRoute() {
switch (true) {
case url.endsWith('/users/authenticate') && method === 'POST':
return authenticate();
case url.endsWith('/users') && method === 'GET':
return getUsers();
default:
// pass through any requests not handled above
return next.handle(request);
}
}
// route functions
function authenticate() {
const { username, password } = body;
const user = users.find(x => x.username === username && x.password === password);
if (!user) return error('Username or password is incorrect');
return ok({
id: user.id,
username: user.username,
firstName: user.firstName,
lastName: user.lastName
})
}
function getUsers() {
if (!isLoggedIn()) return unauthorized();
return ok(users);
}
// helper functions
function ok(body?) {
return of(new HttpResponse({ status: 200, body }))
}
function error(message) {
return throwError({ error: { message } });
}
function unauthorized() {
return throwError({ status: 401, error: { message: 'Unauthorised' } });
}
function isLoggedIn() {
return headers.get('Authorization') === `Basic ${window.btoa('test:test')}`;
}
}
}
export let fakeBackendProvider = {
// use fake backend in place of Http service for backend-less development
provide: HTTP_INTERCEPTORS,
useClass: FakeBackendInterceptor,
multi: true
};
Path: /src/app/_models/user.ts
The user model is a small class that defines the properties of a user.
export class User {
id: number;
username: string;
password: string;
firstName: string;
lastName: string;
authdata?: string;
}
Path: /src/app/_services/authentication.service.ts
The authentication service is used to login & logout of the Angular app, it notifies other components when the user logs in & out, and allows access the currently logged in user.
RxJS Subjects and Observables are used to store the current user object and notify other components when the user logs in and out of the app. Angular components can subscribe() to the public currentUser: Observable property to be notified of changes, and notifications are sent when the this.currentUserSubject.next() method is called in the login() and logout() methods, passing the argument to each subscriber. The RxJS BehaviorSubject is a special type of Subject that keeps hold of the current value and emits it to any new subscribers as soon as they subscribe, while regular Subjects don't store the current value and only emit values that are published after a subscription is created.
The login() method sends the user credentials to the API via an HTTP POST request for authentication. If successful the user's basic authentication data (base64 encoded username and password) is added to the user object and stored in localStorage to keep the user logged in between page refreshes. The user object is then published to all subscribers with the call to this.currentUserSubject.next(user);.
The basic auth data is used by the basic authentication interceptor above to set the authorization header of http requests made to secure api endpoints.
The constructor() of the service initialises the currentUserSubject with the currentUser object from localStorage which enables the user to stay logged in between page refreshes or after the browser is closed. The public currentUser property is then set to this.currentUserSubject.asObservable(); which allows other components to subscribe to the currentUser Observable but doesn't allow them to publish to the currentUserSubject, this is so logging in and out of the app can only be done via the authentication service.
The currentUserValue getter allows other components an easy way to get the value of the currently logged in user without having to subscribe to the currentUser Observable.
The logout() method removes the current user object from local storage and publishes null to the currentUserSubject to notify all subscribers that the user has logged out.
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { BehaviorSubject, Observable } from 'rxjs';
import { map } from 'rxjs/operators';
import { environment } from '@environments/environment';
import { User } from '@app/_models';
@Injectable({ providedIn: 'root' })
export class AuthenticationService {
private currentUserSubject: BehaviorSubject;
public currentUser: Observable;
constructor(private http: HttpClient) {
this.currentUserSubject = new BehaviorSubject(JSON.parse(localStorage.getItem('currentUser')));
this.currentUser = this.currentUserSubject.asObservable();
}
public get currentUserValue(): User {
return this.currentUserSubject.value;
}
login(username: string, password: string) {
return this.http.post(`${environment.apiUrl}/users/authenticate`, { username, password })
.pipe(map(user => {
// store user details and basic auth credentials in local storage to keep user logged in between page refreshes
user.authdata = window.btoa(username + ':' + password);
localStorage.setItem('currentUser', JSON.stringify(user));
this.currentUserSubject.next(user);
return user;
}));
}
logout() {
// remove user from local storage to log user out
localStorage.removeItem('currentUser');
this.currentUserSubject.next(null);
}
}
Path: /src/app/_services/user.service.ts
The user service contains a method for getting all users from the api, I included it to demonstrate accessing a secure api endpoint with the http authorization header set after logging in to the application, the auth header is automatically set with basic authentication credentials by the basic authentication interceptor. The secure endpoint in the example is a fake one implemented in the fake backend provider.
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { environment } from '@environments/environment';
import { User } from '@app/_models';
@Injectable({ providedIn: 'root' })
export class UserService {
constructor(private http: HttpClient) { }
getAll() {
return this.http.get(`${environment.apiUrl}/users`);
}
}
Path: /src/app/home/home.component.html
The home component template contains html and angular 8 template syntax for displaying a simple welcome message and a list of users from a secure api endpoint.
#### You're logged in with Angular 8 & Basic HTTP Authentication!!
###### Users from secure api end point
{{user.firstName}} {{user.lastName}}
Path: /src/app/home/home.component.ts
The home component defines an angular 8 component that gets all users from the user service and makes them available to the template via a users array property.
import { Component } from '@angular/core';
import { first } from 'rxjs/operators';
import { User } from '@app/_models';
import { UserService } from '@app/_services';
@Component({ templateUrl: 'home.component.html' })
export class HomeComponent {
loading = false;
users: User[];
constructor(private userService: UserService) { }
ngOnInit() {
this.loading = true;
this.userService.getAll().pipe(first()).subscribe(users => {
this.loading = false;
this.users = users;
});
}
}
Path: /src/app/login/login.component.html
The login component template contains a login form with username and password fields. It displays validation messages for invalid fields when the submit button is clicked. The form submit event is bound to the onSubmit() method of the login component.
Username: test
Password: test
#### Angular 8 Basic Auth Login Example
Username
Username is required
Password
Password is required
Login
{{error}}
Path: /src/app/login/login.component.ts
The login component uses the authentication service to login to the application. If the user is already logged in they are automatically redirected to the home page.
The loginForm: FormGroup object defines the form controls and validators, and is used to access data entered into the form. The FormGroup is part of the Angular Reactive Forms module and is bound to the login template above with the [formGroup]="loginForm" directive.
import { Component, OnInit } from '@angular/core';
import { Router, ActivatedRoute } from '@angular/router';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import { first } from 'rxjs/operators';
import { AuthenticationService } from '@app/_services';
@Component({ templateUrl: 'login.component.html' })
export class LoginComponent implements OnInit {
loginForm: FormGroup;
loading = false;
submitted = false;
returnUrl: string;
error = '';
constructor(
private formBuilder: FormBuilder,
private route: ActivatedRoute,
private router: Router,
private authenticationService: AuthenticationService
) {
// redirect to home if already logged in
if (this.authenticationService.currentUserValue) {
this.router.navigate(['/']);
}
}
ngOnInit() {
this.loginForm = this.formBuilder.group({
username: ['', Validators.required],
password: ['', Validators.required]
});
// get return url from route parameters or default to '/'
this.returnUrl = this.route.snapshot.queryParams['returnUrl'] || '/';
}
// convenience getter for easy access to form fields
get f() { return this.loginForm.controls; }
onSubmit() {
this.submitted = true;
// stop here if form is invalid
if (this.loginForm.invalid) {
return;
}
this.loading = true;
this.authenticationService.login(this.f.username.value, this.f.password.value)
.pipe(first())
.subscribe(
data => {
this.router.navigate([this.returnUrl]);
},
error => {
this.error = error;
this.loading = false;
});
}
}
Path: /src/app/app.component.html
The app component template is the root component template of the application, it contains the main nav bar which is only displayed for authenticated users, and a router-outlet directive for displaying the contents of each view based on the current route / path.
Home
Logout
Path: /src/app/app.component.ts
The app component is the root component of the application, it defines the root tag of the app as `` with the selector property of the @Component() decorator.
It subscribes to the currentUser observable in the authentication service so it can reactively show/hide the main navigation bar when the user logs in/out of the application. I didn't worry about unsubscribing from the observable here because it's the root component of the application, the only time the component will be destroyed is when the application is closed which would destroy any subscriptions as well.
The app component contains a logout() method which is called from the logout link in the main nav bar above to log the user out and redirect them to the login page.
import { Component } from '@angular/core';
import { Router } from '@angular/router';
import { AuthenticationService } from './_services';
import { User } from './_models';
@Component({ selector: 'app', templateUrl: 'app.component.html' })
export class AppComponent {
currentUser: User;
constructor(
private router: Router,
private authenticationService: AuthenticationService
) {
this.authenticationService.currentUser.subscribe(x => this.currentUser = x);
}
logout() {
this.authenticationService.logout();
this.router.navigate(['/login']);
}
}
Path: /src/app/app.module.ts
The app module defines the root module of the application along with metadata about the module. For more info about angular 8 modules check out this page on the official docs site.
This is where the fake backend provider is added to the application, to switch to a real backend simply remove the providers located below the comment // provider used to create fake backend.
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { ReactiveFormsModule } from '@angular/forms';
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';
// used to create fake backend
import { fakeBackendProvider } from './_helpers';
import { AppComponent } from './app.component';
import { appRoutingModule } from './app.routing';
import { BasicAuthInterceptor, ErrorInterceptor } from './_helpers';
import { HomeComponent } from './home';
import { LoginComponent } from './login';
@NgModule({
imports: [
BrowserModule,
ReactiveFormsModule,
HttpClientModule,
appRoutingModule
],
declarations: [
AppComponent,
HomeComponent,
LoginComponent
],
providers: [
{ provide: HTTP_INTERCEPTORS, useClass: BasicAuthInterceptor, multi: true },
{ provide: HTTP_INTERCEPTORS, useClass: ErrorInterceptor, multi: true },
// provider used to create fake backend
fakeBackendProvider
],
bootstrap: [AppComponent]
})
export class AppModule { }
Path: /src/app/app.routing.ts
Routing for the Angular app is configured as an array of Routes, each component is mapped to a path so the Angular Router knows which component to display based on the URL in the browser address bar. The home route is secured by passing the AuthGuard to the canActivate property of the route.
The Routes array is passed to the RouterModule.forRoot() method which creates a routing module with all of the app routes configured, and also includes all of the Angular Router providers and directives such as the `` directive. For more information on Angular Routing and Navigation see https://angular.io/guide/router.
import { Routes, RouterModule } from '@angular/router';
import { HomeComponent } from './home';
import { LoginComponent } from './login';
import { AuthGuard } from './_helpers';
const routes: Routes = [
{ path: '', component: HomeComponent, canActivate: [AuthGuard] },
{ path: 'login', component: LoginComponent },
// otherwise redirect to home
{ path: '**', redirectTo: '' }
];
export const appRoutingModule = RouterModule.forRoot(routes);
Path: /src/environments/environment.prod.ts
The production environment config contains variables required to run the application in production. This enables you to build the application with a different configuration for each different environment (e.g. production & development) without updating the app code.
When you build the application for production with the command ng build --prod, the output environment.ts is replaced with environment.prod.ts.
export const environment = {
production: true,
apiUrl: 'http://localhost:4000'
};
Path: /src/environments/environment.ts
The development environment config contains variables required to run the application in development.
Environment config is accessed by importing the environment object into any Angular service of component with the line import { environment } from '@environments/environment' and accessing properties on the environment object, see the user service for an example.
export const environment = {
production: false,
apiUrl: 'http://localhost:4000'
};
Path: /src/index.html
The main index.html file is the initial page loaded by the browser that kicks everything off. The Angular CLI (with Webpack under the hood) bundles all of the compiled javascript files together and injects them into the body of the index.html page so the scripts can be loaded and executed by the browser.
Angular 8 - Basic HTTP Authentication Tutorial & Example
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Path: /src/main.ts
The main file is the entry point used by angular to launch and bootstrap the application.
import { enableProdMode } from '@angular/core';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { AppModule } from './app/app.module';
import { environment } from './environments/environment';
if (environment.production) {
enableProdMode();
}
platformBrowserDynamic().bootstrapModule(AppModule)
.catch(err => console.error(err));
Path: /src/polyfills.ts
Some features used by Angular 8 are not yet supported natively by all major browsers, polyfills are used to add support for features where necessary so your Angular 8 application works across all major browsers.
This file is generated by the Angular CLI when creating a new project with the ng new command, I've excluded the comments in the file for brevity.
import 'zone.js/dist/zone';
Path: /src/styles.less
The global styles file contains LESS/CSS styles that are applied globally throughout the application.
/* You can add global styles to this file, and also import other style files */
a { cursor: pointer }
Path: /package.json
The package.json file contains project configuration information including package dependencies which get installed when you run npm install. Full documentation is available on the npm docs website.
{
"name": "angular-8-basic-authentication-example",
"version": "1.0.0",
"scripts": {
"ng": "ng",
"start": "ng serve --open",
"build": "ng build",
"test": "ng test",
"lint": "ng lint",
"e2e": "ng e2e"
},
"private": true,
"dependencies": {
"@angular/animations": "~8.0.1",
"@angular/common": "~8.0.1",
"@angular/compiler": "~8.0.1",
"@angular/core": "~8.0.1",
"@angular/forms": "~8.0.1",
"@angular/platform-browser": "~8.0.1",
"@angular/platform-browser-dynamic": "~8.0.1",
"@angular/router": "~8.0.1",
"rxjs": "~6.4.0",
"tslib": "^1.9.0",
"zone.js": "~0.9.1"
},
"devDependencies": {
"@angular-devkit/build-angular": "~0.800.0",
"@angular/cli": "~8.0.3",
"@angular/compiler-cli": "~8.0.1",
"@angular/language-service": "~8.0.1",
"@types/node": "~8.9.4",
"@types/jasmine": "~3.3.8",
"@types/jasminewd2": "~2.0.3",
"codelyzer": "^5.0.0",
"jasmine-core": "~3.4.0",
"jasmine-spec-reporter": "~4.2.1",
"karma": "~4.1.0",
"karma-chrome-launcher": "~2.2.0",
"karma-coverage-istanbul-reporter": "~2.0.1",
"karma-jasmine": "~2.0.1",
"karma-jasmine-html-reporter": "^1.4.0",
"protractor": "~5.4.0",
"ts-node": "~7.0.0",
"tslint": "~5.15.0",
"typescript": "~3.4.3"
}
}
Path: /tsconfig.json
The tsconfig.json file configures how the TypeScript compiler will convert TypeScript into JavaScript that is understood by the browser. More information is available on the TypeScript docs.
Most of the file is unchanged from when it was generated by the Angular CLI, only the paths property has been added to map @app and @environments to the /src/app and /src/environments directories. This allows imports to be relative to the app and environments folders by prefixing import paths with aliases instead of having to use long relative paths (e.g. import MyComponent from '../../../MyComponent').
{
"compileOnSave": false,
"compilerOptions": {
"baseUrl": "./",
"outDir": "./dist/out-tsc",
"sourceMap": true,
"declaration": false,
"downlevelIteration": true,
"emitDecoratorMetadata": true,
"experimentalDecorators": true,
"module": "esnext",
"moduleResolution": "node",
"importHelpers": true,
"target": "es2015",
"typeRoots": [
"node_modules/@types"
],
"lib": [
"es2018",
"dom"
],
"paths": {
"@app/*": ["src/app/*"],
"@environments/*": ["src/environments/*"]
}
}
}
The tutorial code is available on GitHub
Laravel 5.8 Tutorial - How to build user roles and permissions on Laravel 5.8 App
In this article, you'll learn how to user build roles and permissions on Laravel 5.8 Application. You can do it acl in Laravel 5.8 using spatie composer package. I will explain how to implement User Roles and Permissions(ACL) using spatie/laravel-permission composer package.
In this article, you'll learn how to user build roles and permissions on Laravel 5.8 Application. You can do it acl in Laravel 5.8 using spatie composer package. I will explain how to implement User Roles and Permissions(ACL) using spatie/laravel-permission composer package.
Spatie role permission composer package provide way to create acl in Laravel 5.8. They provide how to assign role to user, how to assign permission to user and how to assign permission assign to roles. I will write step by step creating roles and permissions in Laravel 5.8 application.
Roles and Permissions through you can create several types of users with different role and permission, i mean some user have only see listing of items module, some user can also edit items modules, for delete and etc.
In this examples i created three modules as listed bellow:
- User Management
- Role Management
- Product Management
After register user, you don't have any roles, so you can edit your details and assign admin role to you from User Management. After that you can create your own role with permission like role-list, role-create, role-edit, role-delete, product-list, product-create, product-edit, product-delete. You can check with assign new user and check that.
Step 1: Laravel 5.8 InstallationWe are going from scratch so, If you haven't installed Laravel in your system then you can run bellow command and get fresh Laravel project.
composer create-project --prefer-dist laravel/laravel blog
Now we require to install Spatie package for ACL, that way we can use it's method. Also we will install form collection package. So Open your terminal and run bellow command.
composer require spatie/laravel-permission
composer require laravelcollective/html
Now open config/app.php file and add service provider and aliase.
config/app.php
'providers' => [
....
Spatie\Permission\PermissionServiceProvider::class,
Collective\Html\HtmlServiceProvider::class,
],
'aliases' => [
....
'Form' => Collective\Html\FormFacade::class,
'Html' => Collective\Html\HtmlFacade::class,
],
We can also custom changes on Spatie package, so if you also want to changes then you can fire bellow command and get config file in config/permission.php.
php artisan vendor:publish --provider="Spatie\Permission\PermissionServiceProvider" --tag="config"
In this step we have to create three migrations for as listed bellow tables:
-
users
-
products
-
roles
-
permissions
-
model_has_permissions
-
model_has_roles
-
role_has_permissions
So, if you install fresh project then you have already users table migration but if you don't have products table, so can create manually and other table can create using Spatie package command, so run bellow command and check migration file also.
php artisan vendor:publish --provider="Spatie\Permission\PermissionServiceProvider" --tag="migrations"
php artisan make:migration create_products_table
users table:
<?php
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreateUsersTable extends Migration
{
/**
* Run the migrations.
*
* @return void
*/
public function up()
{
Schema::create('users', function (Blueprint $table) {
$table->bigIncrements('id');
$table->string('name');
$table->string('email');
$table->string('password');
$table->rememberToken();
$table->timestamps();
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::dropIfExists('users');
}
}
products table:
<?php
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreateProductsTable extends Migration
{
/**
* Run the migrations.
*
* @return void
*/
public function up()
{
Schema::create('products', function (Blueprint $table) {
$table->bigIncrements('id');
$table->string('name');
$table->text('detail');
$table->timestamps();
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::dropIfExists('products');
}
}
Spatie tables:
<?php
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreatePermissionTables extends Migration
{
/**
* Run the migrations.
*
* @return void
*/
public function up()
{
$tableNames = config('permission.table_names');
Schema::create($tableNames['permissions'], function (Blueprint $table) {
$table->increments('id');
$table->string('name');
$table->string('guard_name');
$table->timestamps();
});
Schema::create($tableNames['roles'], function (Blueprint $table) {
$table->increments('id');
$table->string('name');
$table->string('guard_name');
$table->timestamps();
});
Schema::create($tableNames['model_has_permissions'], function (Blueprint $table) use ($tableNames) {
$table->integer('permission_id')->unsigned();
$table->morphs('model');
$table->foreign('permission_id')
->references('id')
->on($tableNames['permissions'])
->onDelete('cascade');
$table->primary(['permission_id', 'model_id', 'model_type']);
});
Schema::create($tableNames['model_has_roles'], function (Blueprint $table) use ($tableNames) {
$table->integer('role_id')->unsigned();
$table->morphs('model');
$table->foreign('role_id')
->references('id')
->on($tableNames['roles'])
->onDelete('cascade');
$table->primary(['role_id', 'model_id', 'model_type']);
});
Schema::create($tableNames['role_has_permissions'], function (Blueprint $table) use ($tableNames) {
$table->integer('permission_id')->unsigned();
$table->integer('role_id')->unsigned();
$table->foreign('permission_id')
->references('id')
->on($tableNames['permissions'])
->onDelete('cascade');
$table->foreign('role_id')
->references('id')
->on($tableNames['roles'])
->onDelete('cascade');
$table->primary(['permission_id', 'role_id']);
app('cache')->forget('spatie.permission.cache');
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
$tableNames = config('permission.table_names');
Schema::drop($tableNames['role_has_permissions']);
Schema::drop($tableNames['model_has_roles']);
Schema::drop($tableNames['model_has_permissions']);
Schema::drop($tableNames['roles']);
Schema::drop($tableNames['permissions']);
}
}
Now run migration:
php artisan migrate
In this step we have to create model for User and Product table, so if you get fresh project then you have User Model have so just replace code and other you should create.
app/User.php
<?php
namespace App;
use Illuminate\Notifications\Notifiable;
use Illuminate\Contracts\Auth\MustVerifyEmail;
use Illuminate\Foundation\Auth\User as Authenticatable;
use Spatie\Permission\Traits\HasRoles;
class User extends Authenticatable
{
use Notifiable;
use HasRoles;
/**
* The attributes that are mass assignable.
*
* @var array
*/
protected $fillable = [
'name', 'email', 'password',
];
/**
* The attributes that should be hidden for arrays.
*
* @var array
*/
protected $hidden = [
'password', 'remember_token',
];
/**
* The attributes that should be cast to native types.
*
* @var array
*/
protected $casts = [
'email_verified_at' => 'datetime',
];
}
app/Product.php
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Product extends Model
{
/**
* The attributes that are mass assignable.
*
* @var array
*/
protected $fillable = [
'name', 'detail'
];
}
Spatie package provide it's in-built middleware that way we can use it simply and that is display as bellow:
role
permission
So, we have to add middleware in Kernel.php file this way :
app/Http/Kernel.php
....
protected $routeMiddleware = [
....
'role' => \Spatie\Permission\Middlewares\RoleMiddleware::class,
'permission' => \Spatie\Permission\Middlewares\PermissionMiddleware::class,
]
....
In this step we require to create authentication of Laravel 5.8, so laravel provide artisan command to create authentication that way we don't require to create route and controller for login and registration. so run bellow command:
php artisan make:auth
We require to add number of route for users module, products module and roles module. In this this route i also use middleware with permission for roles and products route, so add route this way:
routes/web.php
Auth::routes();
Route::get('/home', '[email protected]')->name('home');
Route::group(['middleware' => ['auth']], function() {
Route::resource('roles','RoleController');
Route::resource('users','UserController');
Route::resource('products','ProductController');
});
In this step we have add three controller for users module, products module and roles module so you can create three controller like as bellow:
app/Http/Controllers/UserController.php
<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Http\Controllers\Controller;
use App\User;
use Spatie\Permission\Models\Role;
use DB;
use Hash;
class UserController extends Controller
{
/**
* Display a listing of the resource.
*
* @return \Illuminate\Http\Response
*/
public function index(Request $request)
{
$data = User::orderBy('id','DESC')->paginate(5);
return view('users.index',compact('data'))
->with('i', ($request->input('page', 1) - 1) * 5);
}
/**
* Show the form for creating a new resource.
*
* @return \Illuminate\Http\Response
*/
public function create()
{
$roles = Role::pluck('name','name')->all();
return view('users.create',compact('roles'));
}
/**
* Store a newly created resource in storage.
*
* @param \Illuminate\Http\Request $request
* @return \Illuminate\Http\Response
*/
public function store(Request $request)
{
$this->validate($request, [
'name' => 'required',
'email' => 'required|email|unique:users,email',
'password' => 'required|same:confirm-password',
'roles' => 'required'
]);
$input = $request->all();
$input['password'] = Hash::make($input['password']);
$user = User::create($input);
$user->assignRole($request->input('roles'));
return redirect()->route('users.index')
->with('success','User created successfully');
}
/**
* Display the specified resource.
*
* @param int $id
* @return \Illuminate\Http\Response
*/
public function show($id)
{
$user = User::find($id);
return view('users.show',compact('user'));
}
/**
* Show the form for editing the specified resource.
*
* @param int $id
* @return \Illuminate\Http\Response
*/
public function edit($id)
{
$user = User::find($id);
$roles = Role::pluck('name','name')->all();
$userRole = $user->roles->pluck('name','name')->all();
return view('users.edit',compact('user','roles','userRole'));
}
/**
* Update the specified resource in storage.
*
* @param \Illuminate\Http\Request $request
* @param int $id
* @return \Illuminate\Http\Response
*/
public function update(Request $request, $id)
{
$this->validate($request, [
'name' => 'required',
'email' => 'required|email|unique:users,email,'.$id,
'password' => 'same:confirm-password',
'roles' => 'required'
]);
$input = $request->all();
if(!empty($input['password'])){
$input['password'] = Hash::make($input['password']);
}else{
$input = array_except($input,array('password'));
}
$user = User::find($id);
$user->update($input);
DB::table('model_has_roles')->where('model_id',$id)->delete();
$user->assignRole($request->input('roles'));
return redirect()->route('users.index')
->with('success','User updated successfully');
}
/**
* Remove the specified resource from storage.
*
* @param int $id
* @return \Illuminate\Http\Response
*/
public function destroy($id)
{
User::find($id)->delete();
return redirect()->route('users.index')
->with('success','User deleted successfully');
}
}
app/Http/Controllers/ProductController.php
<?php
namespace App\Http\Controllers;
use App\Product;
use Illuminate\Http\Request;
class ProductController extends Controller
{
/**
* Display a listing of the resource.
*
* @return \Illuminate\Http\Response
*/
function __construct()
{
$this->middleware('permission:product-list|product-create|product-edit|product-delete', ['only' => ['index','show']]);
$this->middleware('permission:product-create', ['only' => ['create','store']]);
$this->middleware('permission:product-edit', ['only' => ['edit','update']]);
$this->middleware('permission:product-delete', ['only' => ['destroy']]);
}
/**
* Display a listing of the resource.
*
* @return \Illuminate\Http\Response
*/
public function index()
{
$products = Product::latest()->paginate(5);
return view('products.index',compact('products'))
->with('i', (request()->input('page', 1) - 1) * 5);
}
/**
* Show the form for creating a new resource.
*
* @return \Illuminate\Http\Response
*/
public function create()
{
return view('products.create');
}
/**
* Store a newly created resource in storage.
*
* @param \Illuminate\Http\Request $request
* @return \Illuminate\Http\Response
*/
public function store(Request $request)
{
request()->validate([
'name' => 'required',
'detail' => 'required',
]);
Product::create($request->all());
return redirect()->route('products.index')
->with('success','Product created successfully.');
}
/**
* Display the specified resource.
*
* @param \App\Product $product
* @return \Illuminate\Http\Response
*/
public function show(Product $product)
{
return view('products.show',compact('product'));
}
/**
* Show the form for editing the specified resource.
*
* @param \App\Product $product
* @return \Illuminate\Http\Response
*/
public function edit(Product $product)
{
return view('products.edit',compact('product'));
}
/**
* Update the specified resource in storage.
*
* @param \Illuminate\Http\Request $request
* @param \App\Product $product
* @return \Illuminate\Http\Response
*/
public function update(Request $request, Product $product)
{
request()->validate([
'name' => 'required',
'detail' => 'required',
]);
$product->update($request->all());
return redirect()->route('products.index')
->with('success','Product updated successfully');
}
/**
* Remove the specified resource from storage.
*
* @param \App\Product $product
* @return \Illuminate\Http\Response
*/
public function destroy(Product $product)
{
$product->delete();
return redirect()->route('products.index')
->with('success','Product deleted successfully');
}
}
app/Http/Controllers/RoleController.php
<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Http\Controllers\Controller;
use Spatie\Permission\Models\Role;
use Spatie\Permission\Models\Permission;
use DB;
class RoleController extends Controller
{
/**
* Display a listing of the resource.
*
* @return \Illuminate\Http\Response
*/
function __construct()
{
$this->middleware('permission:role-list|role-create|role-edit|role-delete', ['only' => ['index','store']]);
$this->middleware('permission:role-create', ['only' => ['create','store']]);
$this->middleware('permission:role-edit', ['only' => ['edit','update']]);
$this->middleware('permission:role-delete', ['only' => ['destroy']]);
}
/**
* Display a listing of the resource.
*
* @return \Illuminate\Http\Response
*/
public function index(Request $request)
{
$roles = Role::orderBy('id','DESC')->paginate(5);
return view('roles.index',compact('roles'))
->with('i', ($request->input('page', 1) - 1) * 5);
}
/**
* Show the form for creating a new resource.
*
* @return \Illuminate\Http\Response
*/
public function create()
{
$permission = Permission::get();
return view('roles.create',compact('permission'));
}
/**
* Store a newly created resource in storage.
*
* @param \Illuminate\Http\Request $request
* @return \Illuminate\Http\Response
*/
public function store(Request $request)
{
$this->validate($request, [
'name' => 'required|unique:roles,name',
'permission' => 'required',
]);
$role = Role::create(['name' => $request->input('name')]);
$role->syncPermissions($request->input('permission'));
return redirect()->route('roles.index')
->with('success','Role created successfully');
}
/**
* Display the specified resource.
*
* @param int $id
* @return \Illuminate\Http\Response
*/
public function show($id)
{
$role = Role::find($id);
$rolePermissions = Permission::join("role_has_permissions","role_has_permissions.permission_id","=","permissions.id")
->where("role_has_permissions.role_id",$id)
->get();
return view('roles.show',compact('role','rolePermissions'));
}
/**
* Show the form for editing the specified resource.
*
* @param int $id
* @return \Illuminate\Http\Response
*/
public function edit($id)
{
$role = Role::find($id);
$permission = Permission::get();
$rolePermissions = DB::table("role_has_permissions")->where("role_has_permissions.role_id",$id)
->pluck('role_has_permissions.permission_id','role_has_permissions.permission_id')
->all();
return view('roles.edit',compact('role','permission','rolePermissions'));
}
/**
* Update the specified resource in storage.
*
* @param \Illuminate\Http\Request $request
* @param int $id
* @return \Illuminate\Http\Response
*/
public function update(Request $request, $id)
{
$this->validate($request, [
'name' => 'required',
'permission' => 'required',
]);
$role = Role::find($id);
$role->name = $request->input('name');
$role->save();
$role->syncPermissions($request->input('permission'));
return redirect()->route('roles.index')
->with('success','Role updated successfully');
}
/**
* Remove the specified resource from storage.
*
* @param int $id
* @return \Illuminate\Http\Response
*/
public function destroy($id)
{
DB::table("roles")->where('id',$id)->delete();
return redirect()->route('roles.index')
->with('success','Role deleted successfully');
}
}
This is last step we have to add numbers view for layouts, users module, roles module, products modules and errors page, so create number of view like as bellow:
resources/views/layouts/app.blade.php
<html lang="{{ app()->getLocale() }}">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<!-- CSRF Token -->
<meta name="csrf-token" content="{{ csrf_token() }}">
<title>{{ config('app.name', 'Laravel 5.8 User Roles and Permissions Tutorial') }}</title>
<!-- Scripts -->
<script src="{{ asset('js/app.js') }}" defer></script>
<!-- Fonts -->
<link rel="dns-prefetch" href="https://fonts.gstatic.com">
<link href="https://fonts.googleapis.com/css?family=Raleway:300,400,600" rel="stylesheet" type="text/css">
<!-- Styles -->
<link href="{{ asset('css/app.css') }}" rel="stylesheet">
</head>
<body>
<div id="app">
<nav class="navbar navbar-expand-md navbar-light navbar-laravel">
<div class="container">
<a class="navbar-brand" href="{{ url('/') }}">
Laravel 5.8 User Roles and Permissions - ItSolutionStuff.com
</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<!-- Left Side Of Navbar -->
<ul class="navbar-nav mr-auto"></ul>
<!-- Right Side Of Navbar -->
<ul class="navbar-nav ml-auto">
<!-- Authentication Links -->
@guest
<li><a class="nav-link" href="{{ route('login') }}">{{ __('Login') }}</a></li>
<li><a class="nav-link" href="{{ route('register') }}">{{ __('Register') }}</a></li>
@else
<li><a class="nav-link" href="{{ route('users.index') }}">Manage Users</a></li>
<li><a class="nav-link" href="{{ route('roles.index') }}">Manage Role</a></li>
<li><a class="nav-link" href="{{ route('products.index') }}">Manage Product</a></li>
<li class="nav-item dropdown">
<a id="navbarDropdown" class="nav-link dropdown-toggle" href="#" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false" v-pre>
{{ Auth::user()->name }} <span class="caret"></span>
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="{{ route('logout') }}"
onclick="event.preventDefault();
document.getElementById('logout-form').submit();">
{{ __('Logout') }}
</a>
<form id="logout-form" action="{{ route('logout') }}" method="POST" style="display: none;">
@csrf
</form>
</div>
</li>
@endguest
</ul>
</div>
</div>
</nav>
<main class="py-4">
<div class="container">
@yield('content')
</div>
</main>
</div>
</body>
</html>
resources/views/users/index.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2>Users Management</h2>
</div>
<div class="pull-right">
<a class="btn btn-success" href="{{ route('users.create') }}"> Create New User</a>
</div>
</div>
</div>
@if ($message = Session::get('success'))
<div class="alert alert-success">
<p>{{ $message }}</p>
</div>
@endif
<table class="table table-bordered">
<tr>
<th>No</th>
<th>Name</th>
<th>Email</th>
<th>Roles</th>
<th width="280px">Action</th>
</tr>
@foreach ($data as $key => $user)
<tr>
<td>{{ ++$i }}</td>
<td>{{ $user->name }}</td>
<td>{{ $user->email }}</td>
<td>
@if(!empty($user->getRoleNames()))
@foreach($user->getRoleNames() as $v)
<label class="badge badge-success">{{ $v }}</label>
@endforeach
@endif
</td>
<td>
<a class="btn btn-info" href="{{ route('users.show',$user->id) }}">Show</a>
<a class="btn btn-primary" href="{{ route('users.edit',$user->id) }}">Edit</a>
{!! Form::open(['method' => 'DELETE','route' => ['users.destroy', $user->id],'style'=>'display:inline']) !!}
{!! Form::submit('Delete', ['class' => 'btn btn-danger']) !!}
{!! Form::close() !!}
</td>
</tr>
@endforeach
</table>
{!! $data->render() !!}
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
@endsection
resources/views/users/create.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2>Create New User</h2>
</div>
<div class="pull-right">
<a class="btn btn-primary" href="{{ route('users.index') }}"> Back</a>
</div>
</div>
</div>
@if (count($errors) > 0)
<div class="alert alert-danger">
<strong>Whoops!</strong> There were some problems with your input.<br><br>
<ul>
@foreach ($errors->all() as $error)
<li>{{ $error }}</li>
@endforeach
</ul>
</div>
@endif
{!! Form::open(array('route' => 'users.store','method'=>'POST')) !!}
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Name:</strong>
{!! Form::text('name', null, array('placeholder' => 'Name','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Email:</strong>
{!! Form::text('email', null, array('placeholder' => 'Email','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Password:</strong>
{!! Form::password('password', array('placeholder' => 'Password','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Confirm Password:</strong>
{!! Form::password('confirm-password', array('placeholder' => 'Confirm Password','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Role:</strong>
{!! Form::select('roles[]', $roles,[], array('class' => 'form-control','multiple')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12 text-center">
<button type="submit" class="btn btn-primary">Submit</button>
</div>
</div>
{!! Form::close() !!}
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
@endsection
resources/views/users/edit.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2>Edit New User</h2>
</div>
<div class="pull-right">
<a class="btn btn-primary" href="{{ route('users.index') }}"> Back</a>
</div>
</div>
</div>
@if (count($errors) > 0)
<div class="alert alert-danger">
<strong>Whoops!</strong> There were some problems with your input.<br><br>
<ul>
@foreach ($errors->all() as $error)
<li>{{ $error }}</li>
@endforeach
</ul>
</div>
@endif
{!! Form::model($user, ['method' => 'PATCH','route' => ['users.update', $user->id]]) !!}
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Name:</strong>
{!! Form::text('name', null, array('placeholder' => 'Name','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Email:</strong>
{!! Form::text('email', null, array('placeholder' => 'Email','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Password:</strong>
{!! Form::password('password', array('placeholder' => 'Password','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Confirm Password:</strong>
{!! Form::password('confirm-password', array('placeholder' => 'Confirm Password','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Role:</strong>
{!! Form::select('roles[]', $roles,$userRole, array('class' => 'form-control','multiple')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12 text-center">
<button type="submit" class="btn btn-primary">Submit</button>
</div>
</div>
{!! Form::close() !!}
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
@endsection
resources/views/users/show.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2> Show User</h2>
</div>
<div class="pull-right">
<a class="btn btn-primary" href="{{ route('users.index') }}"> Back</a>
</div>
</div>
</div>
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Name:</strong>
{{ $user->name }}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Email:</strong>
{{ $user->email }}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Roles:</strong>
@if(!empty($user->getRoleNames()))
@foreach($user->getRoleNames() as $v)
<label class="badge badge-success">{{ $v }}</label>
@endforeach
@endif
</div>
</div>
</div>
@endsection
resources/views/roles/index.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2>Role Management</h2>
</div>
<div class="pull-right">
@can('role-create')
<a class="btn btn-success" href="{{ route('roles.create') }}"> Create New Role</a>
@endcan
</div>
</div>
</div>
@if ($message = Session::get('success'))
<div class="alert alert-success">
<p>{{ $message }}</p>
</div>
@endif
<table class="table table-bordered">
<tr>
<th>No</th>
<th>Name</th>
<th width="280px">Action</th>
</tr>
@foreach ($roles as $key => $role)
<tr>
<td>{{ ++$i }}</td>
<td>{{ $role->name }}</td>
<td>
<a class="btn btn-info" href="{{ route('roles.show',$role->id) }}">Show</a>
@can('role-edit')
<a class="btn btn-primary" href="{{ route('roles.edit',$role->id) }}">Edit</a>
@endcan
@can('role-delete')
{!! Form::open(['method' => 'DELETE','route' => ['roles.destroy', $role->id],'style'=>'display:inline']) !!}
{!! Form::submit('Delete', ['class' => 'btn btn-danger']) !!}
{!! Form::close() !!}
@endcan
</td>
</tr>
@endforeach
</table>
{!! $roles->render() !!}
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
@endsection
resources/views/roles/create.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2>Create New Role</h2>
</div>
<div class="pull-right">
<a class="btn btn-primary" href="{{ route('roles.index') }}"> Back</a>
</div>
</div>
</div>
@if (count($errors) > 0)
<div class="alert alert-danger">
<strong>Whoops!</strong> There were some problems with your input.<br><br>
<ul>
@foreach ($errors->all() as $error)
<li>{{ $error }}</li>
@endforeach
</ul>
</div>
@endif
{!! Form::open(array('route' => 'roles.store','method'=>'POST')) !!}
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Name:</strong>
{!! Form::text('name', null, array('placeholder' => 'Name','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Permission:</strong>
<br/>
@foreach($permission as $value)
<label>{{ Form::checkbox('permission[]', $value->id, false, array('class' => 'name')) }}
{{ $value->name }}</label>
<br/>
@endforeach
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12 text-center">
<button type="submit" class="btn btn-primary">Submit</button>
</div>
</div>
{!! Form::close() !!}
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
@endsection
resources/views/roles/edit.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2>Edit Role</h2>
</div>
<div class="pull-right">
<a class="btn btn-primary" href="{{ route('roles.index') }}"> Back</a>
</div>
</div>
</div>
@if (count($errors) > 0)
<div class="alert alert-danger">
<strong>Whoops!</strong> There were some problems with your input.<br><br>
<ul>
@foreach ($errors->all() as $error)
<li>{{ $error }}</li>
@endforeach
</ul>
</div>
@endif
{!! Form::model($role, ['method' => 'PATCH','route' => ['roles.update', $role->id]]) !!}
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Name:</strong>
{!! Form::text('name', null, array('placeholder' => 'Name','class' => 'form-control')) !!}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Permission:</strong>
<br/>
@foreach($permission as $value)
<label>{{ Form::checkbox('permission[]', $value->id, in_array($value->id, $rolePermissions) ? true : false, array('class' => 'name')) }}
{{ $value->name }}</label>
<br/>
@endforeach
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12 text-center">
<button type="submit" class="btn btn-primary">Submit</button>
</div>
</div>
{!! Form::close() !!}
@endsection
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
resources/views/roles/show.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2> Show Role</h2>
</div>
<div class="pull-right">
<a class="btn btn-primary" href="{{ route('roles.index') }}"> Back</a>
</div>
</div>
</div>
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Name:</strong>
{{ $role->name }}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Permissions:</strong>
@if(!empty($rolePermissions))
@foreach($rolePermissions as $v)
<label class="label label-success">{{ $v->name }},</label>
@endforeach
@endif
</div>
</div>
</div>
@endsection
resources/views/products/index.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2>Products</h2>
</div>
<div class="pull-right">
@can('product-create')
<a class="btn btn-success" href="{{ route('products.create') }}"> Create New Product</a>
@endcan
</div>
</div>
</div>
@if ($message = Session::get('success'))
<div class="alert alert-success">
<p>{{ $message }}</p>
</div>
@endif
<table class="table table-bordered">
<tr>
<th>No</th>
<th>Name</th>
<th>Details</th>
<th width="280px">Action</th>
</tr>
@foreach ($products as $product)
<tr>
<td>{{ ++$i }}</td>
<td>{{ $product->name }}</td>
<td>{{ $product->detail }}</td>
<td>
<form action="{{ route('products.destroy',$product->id) }}" method="POST">
<a class="btn btn-info" href="{{ route('products.show',$product->id) }}">Show</a>
@can('product-edit')
<a class="btn btn-primary" href="{{ route('products.edit',$product->id) }}">Edit</a>
@endcan
@csrf
@method('DELETE')
@can('product-delete')
<button type="submit" class="btn btn-danger">Delete</button>
@endcan
</form>
</td>
</tr>
@endforeach
</table>
{!! $products->links() !!}
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
@endsection
resources/views/products/create.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2>Add New Product</h2>
</div>
<div class="pull-right">
<a class="btn btn-primary" href="{{ route('products.index') }}"> Back</a>
</div>
</div>
</div>
@if ($errors->any())
<div class="alert alert-danger">
<strong>Whoops!</strong> There were some problems with your input.<br><br>
<ul>
@foreach ($errors->all() as $error)
<li>{{ $error }}</li>
@endforeach
</ul>
</div>
@endif
<form action="{{ route('products.store') }}" method="POST">
@csrf
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Name:</strong>
<input type="text" name="name" class="form-control" placeholder="Name">
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Detail:</strong>
<textarea class="form-control" style="height:150px" name="detail" placeholder="Detail"></textarea>
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12 text-center">
<button type="submit" class="btn btn-primary">Submit</button>
</div>
</div>
</form>
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
@endsection
resources/views/products/edit.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2>Edit Product</h2>
</div>
<div class="pull-right">
<a class="btn btn-primary" href="{{ route('products.index') }}"> Back</a>
</div>
</div>
</div>
@if ($errors->any())
<div class="alert alert-danger">
<strong>Whoops!</strong> There were some problems with your input.<br><br>
<ul>
@foreach ($errors->all() as $error)
<li>{{ $error }}</li>
@endforeach
</ul>
</div>
@endif
<form action="{{ route('products.update',$product->id) }}" method="POST">
@csrf
@method('PUT')
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Name:</strong>
<input type="text" name="name" value="{{ $product->name }}" class="form-control" placeholder="Name">
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Detail:</strong>
<textarea class="form-control" style="height:150px" name="detail" placeholder="Detail">{{ $product->detail }}</textarea>
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12 text-center">
<button type="submit" class="btn btn-primary">Submit</button>
</div>
</div>
</form>
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
@endsection
resources/views/products/show.blade.php
@extends('layouts.app')
@section('content')
<div class="row">
<div class="col-lg-12 margin-tb">
<div class="pull-left">
<h2> Show Product</h2>
</div>
<div class="pull-right">
<a class="btn btn-primary" href="{{ route('products.index') }}"> Back</a>
</div>
</div>
</div>
<div class="row">
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Name:</strong>
{{ $product->name }}
</div>
</div>
<div class="col-xs-12 col-sm-12 col-md-12">
<div class="form-group">
<strong>Details:</strong>
{{ $product->detail }}
</div>
</div>
</div>
@endsection
<p class="text-center text-primary"><small>Tutorial by ItSolutionStuff.com</small></p>
Now, in this step we will handle exertion. if you don't have a permission and try to access that page using browser url then you can give message as like bellow:
add/Exceptions/Handler.php
......
public function render($request, Exception $exception)
{
if ($exception instanceof \Spatie\Permission\Exceptions\UnauthorizedException) {
return response()->json(['User have not permission for this page access.']);
}
return parent::render($request, $exception);
}
....
In this step we will create seeder for permissions, Right now we have fixed permission so we create using seeder as listed bellow, but if you can add more permission as you want:
1.role-list
2.role-create
3.role-edit
4.role-delete
5.product-list
6.product-create
7.product-edit
8.product-delete
So, first create seeder using bellow command:
php artisan make:seeder PermissionTableSeeder
And put bellow code in PermissionTableSeeder seeder this way:
database/seeds/PermissionTableSeeder.php
<?php
use Illuminate\Database\Seeder;
use Spatie\Permission\Models\Permission;
class PermissionTableSeeder extends Seeder
{
/**
* Run the database seeds.
*
* @return void
*/
public function run()
{
$permissions = [
'role-list',
'role-create',
'role-edit',
'role-delete',
'product-list',
'product-create',
'product-edit',
'product-delete'
];
foreach ($permissions as $permission) {
Permission::create(['name' => $permission]);
}
}
}
After this we have to run bellow command for run PermissionTableSeeder seeder:
php artisan db:seed --class=PermissionTableSeeder
Now let's create new seeder for creating admin user.
php artisan make:seeder CreateAdminUserSeeder
database/seeds/PermissionTableSeeder.php
<?php
use Illuminate\Database\Seeder;
use App\User;
use Spatie\Permission\Models\Role;
use Spatie\Permission\Models\Permission;
class CreateAdminUserSeeder extends Seeder
{
/**
* Run the database seeds.
*
* @return void
*/
public function run()
{
$user = User::create([
'name' => 'Hardik Savani',
'email' => '[email protected]',
'password' => bcrypt('123456')
]);
$role = Role::create(['name' => 'Admin']);
$permissions = Permission::pluck('id','id')->all();
$role->syncPermissions($permissions);
$user->assignRole([$role->id]);
}
}
php artisan db:seed --class=CreateAdminUserSeeder
Now we are ready to to run full example of ACL. so let's run our example so run bellow command for quick run:
php artisan serve
Access By
http://localhost:8000/
Now you can login with following credential:
Email: [email protected]
Password: 123456
You can see bellow screenshots:
You can download code from GitHub
Creating a Modal Dialog in Angular 8 with TypeScript
In this tutorial we'll cover how to implement modal windows (dialog boxes) in Angular 8 with TypeScript. The example is a custom modal without the need for any 3rd party libraries.
There are plenty of plugins and libraries out there that include modal windows, in the past I used them myself when I needed to add a modal to a new project. The main issue I have with 3rd party plugins is that they usually contain a lot of features I don't need which adds unnecessary bloat to my Angular app, so a while ago I took some time to implement a custom modal window to see how difficult it would be and also to remove the magic & mystery I had in my mind about exactly how modals work.
When I finished I was pleasantly surprised at the relatively small amount of code required to implement a custom modal window, most of the modal 'magic' is done with a handful of CSS styles (see modal.component.less) while Angular / TypeScript is just used for showing and hiding the modal windows.
- Install NodeJS and NPM from https://nodejs.org/en/download/.
- Download or clone the project source code from https://github.com/cornflourblue/angular-8-custom-modal
- Install all required npm packages by running
npm installfrom the command line in the project root folder (where the package.json is located). - Start the application by running
npm startfrom the command line in the project root folder.
NOTE: You can also run the app directly using the Angular CLI command ng serve --open. To do this first install the Angular CLI globally on your system with the command npm install -g @angular/cli.
To add modals to your Angular 8 application you'll need to copy the /src/app/_modal folder and contents from the example project, the folder contains the modal module and associated files, including:
modal.model.less- LESS/CSS styles for displaying modal dialogs, this is where the modal "magic" happens.modal.component.html- modal component template that contains the wrapper html for displaying modal dialogs.modal.component.ts- modal component with the logic for displaying modal dialogs.modal.module.ts- modal module that encapsulates the modal component so it can be imported by the app module.modal.service.ts- modal service that can be used by any angular component to open and close modal dialogs.index.ts- barrel file that re-exports the modal module and service so they can be imported using only the folder path instead of the full path to each file, and also enables importing from multiple files with a single import.
Import the Modal Module into your App Module
To make the modal component available to your Angular 8 application you need to add the ModalModule to the imports array of your App Module (app.module.ts). See the app module from the example app below, the modal module is imported on line 5 and added to the imports array of the app module on line 16.
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { ModalModule } from './_modal';
import { appRoutingModule } from './app.routing';
import { AppComponent } from './app.component';
import { HomeComponent } from './home';
import { TestPageComponent } from './test-page';
@NgModule({
imports: [
BrowserModule,
FormsModule,
ModalModule,
appRoutingModule
],
declarations: [
AppComponent,
HomeComponent,
TestPageComponent
],
bootstrap: [AppComponent]
})
export class AppModule { }
Add the tag to pages where you want to display modals
To add a modal dialog to any page simply add the <jw-modal id="[insert unique id]"></jw-modal> tag along with the content for the modal. You can put any content you like inside the <jw-modal> element. You can also update the modal LESS/CSS if you want to change the styles of the modals, e.g to make them smaller or add CSS animation transitions.
IMPORTANT: A unique id is required for each modal on a page, it can be any string e.g. 'custom-modal-1'. The id string is used by the modal service to keep track of each active modal in the angular app, so the service knows which modal to open/close based on the id passed to the modalService.open() and modalService.close() methods e.g. modalService.open('custom-modal-1').
Here is the home component template from the example app (/src/app/home/home.component.html) that contains two modals, each is opened by a button click, and the first modal contains an input text field that allows you to edit the bodyText displayed in the template.
<div>
<h1>Home</h1>
<p>{{bodyText}}</p>
<button (click)="openModal('custom-modal-1')">Open Modal 1</button>
<button (click)="openModal('custom-modal-2')">Open Modal 2</button>
</div>
<jw-modal id="custom-modal-1">
<h1>A Custom Modal!</h1>
<p>Home page text: <input type="text" [(ngModel)]="bodyText" /></p>
<button (click)="closeModal('custom-modal-1');">Close</button>
</jw-modal>
<jw-modal id="custom-modal-2">
<h1 style="height:1000px">A Tall Custom Modal!</h1>
<button (click)="closeModal('custom-modal-2');">Close</button>
</jw-modal>
Opening & Closing Angular 8 Modal Dialogs
To open a modal call the modalService.open() method with the id of the modal you want to open, e.g. modalService.open('custom-modal-1'). To close a modal call the modalService.close() method with the id of the modal you want to close, e.g. modalService.close('custom-modal-1').
By default modals are closed on background click, to disable this remove the chunk of code in the modal component (/src/app/_modal/modal.component.ts) located directly below the comment // close modal on background click.
Here is the home component from the example app (/src/app/home/home.component.ts), it contains methods for opening and closing modals (openModal() and closeModal()) that call the corresponding methods of the modal service.
import { Component, OnInit } from '@angular/core';
import { ModalService } from '../_modal';
@Component({ templateUrl: 'home.component.html' })
export class HomeComponent implements OnInit {
bodyText: string;
constructor(private modalService: ModalService) { }
ngOnInit() {
this.bodyText = 'This text can be updated in modal 1';
}
openModal(id: string) {
this.modalService.open(id);
}
closeModal(id: string) {
this.modalService.close(id);
}
}
Below is a breakdown of the pieces of code used to implement custom modal dialogs in Angular 8 & TypeScript, you don't need to know the details of how it all works to use the modals in your project, it's only if you're interested in the nuts and bolts or if you want to modify the underlying code or behaviour.
LESS/CSS Styles for Angular 8 Modal DialogsThese are the styles applied to the custom modal dialogs in this example, they could also be used in non-angular projects as it's just pure LESS/CSS.
I prefixed the modal element and classes with jw- to prevent conflicts with 3rd party css libraries such as Bootstrap.
/* MODAL STYLES
-------------------------------*/
jw-modal {
/* modals are hidden by default */
display: none;
.jw-modal {
/* modal container fixed across whole screen */
position: fixed;
top: 0;
right: 0;
bottom: 0;
left: 0;
/* z-index must be higher than .jw-modal-background */
z-index: 1000;
/* enables scrolling for tall modals */
overflow: auto;
.jw-modal-body {
padding: 20px;
background: #fff;
/* margin exposes part of the modal background */
margin: 40px;
}
}
.jw-modal-background {
/* modal background fixed across whole screen */
position: fixed;
top: 0;
right: 0;
bottom: 0;
left: 0;
/* semi-transparent black */
background-color: #000;
opacity: 0.75;
/* z-index must be below .jw-modal and above everything else */
z-index: 900;
}
}
body.jw-modal-open {
/* body overflow is hidden to hide main scrollbar when modal window is open */
overflow: hidden;
}
The Angular 8 modal service manages the communication that's required between page components and modal components. It maintains a list of available modals on the page and exposes methods for interacting with those modals.
import { Injectable } from '@angular/core';
@Injectable({ providedIn: 'root' })
export class ModalService {
private modals: any[] = [];
add(modal: any) {
// add modal to array of active modals
this.modals.push(modal);
}
remove(id: string) {
// remove modal from array of active modals
this.modals = this.modals.filter(x => x.id !== id);
}
open(id: string) {
// open modal specified by id
const modal = this.modals.find(x => x.id === id);
modal.open();
}
close(id: string) {
// close modal specified by id
const modal = this.modals.find(x => x.id === id);
modal.close();
}
}
The custom modal component is used to add modal windows anywhere in your angular application by using the <jw-modal> tag. Each modal instance adds itself to the modal service when it loads by calling modalService.add(this) from the ngOnInit Angular lifecycle method, and removes itself from the modal service when it is destroyed by calling modalService.remove(this.id) from the ngOnDestroy Angular lifecycle method.
import { Component, ViewEncapsulation, ElementRef, Input, OnInit, OnDestroy } from '@angular/core';
import { ModalService } from './modal.service';
@Component({
selector: 'jw-modal',
templateUrl: 'modal.component.html',
styleUrls: ['modal.component.less'],
encapsulation: ViewEncapsulation.None
})
export class ModalComponent implements OnInit, OnDestroy {
@Input() id: string;
private element: any;
constructor(private modalService: ModalService, private el: ElementRef) {
this.element = el.nativeElement;
}
ngOnInit(): void {
// ensure id attribute exists
if (!this.id) {
console.error('modal must have an id');
return;
}
// move element to bottom of page (just before </body>) so it can be displayed above everything else
document.body.appendChild(this.element);
// close modal on background click
this.element.addEventListener('click', el => {
if (el.target.className === 'jw-modal') {
this.close();
}
});
// add self (this modal instance) to the modal service so it's accessible from controllers
this.modalService.add(this);
}
// remove self from modal service when component is destroyed
ngOnDestroy(): void {
this.modalService.remove(this.id);
this.element.remove();
}
// open modal
open(): void {
this.element.style.display = 'block';
document.body.classList.add('jw-modal-open');
}
// close modal
close(): void {
this.element.style.display = 'none';
document.body.classList.remove('jw-modal-open');
}
}
The modal component template contains just a couple of wrapper divs for the modal content and a div for the modal background. The <ng-content> element is replaced by Angular with the contents you set inside the <jw-modal> element, this is called Angular content projection.
<div class="jw-modal">
<div class="jw-modal-body">
<ng-content></ng-content>
</div>
</div>
<div class="jw-modal-background"></div>
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Further reading about AngularJS
☞ Angular 8 (formerly Angular 2) - The Complete Guide
☞ Angular & NodeJS - The MEAN Stack Guide
☞ The Complete Node.js Developer Course (3rd Edition)
☞ Best 50 Angular Interview Questions for Frontend Developers in 2019
☞ MEAN Stack Angular 8 CRUD Web Application
☞ Angular 8 Tutorial - User Registration and Login Example
☞ How to build a CRUD Web App with Angular 8.0