Getting Started with Vuex: a Beginner’s Guide

Getting Started with Vuex: a Beginner’s Guide

In this article, we’ve looked at what Vuex is, what problem it solves, how to install it, as well as its core concepts. We then applied these concepts to refactor our counter app to work with Vuex. Hopefully this introduction will serve you well in implementing Vuex in your own projects.

Handling state in single-page apps can be a tricky process. As an application gets larger and more complex, you start to encounter situations where a given piece of state needs to be used in multiple components, or you find yourself passing state through components that don’t need it, just to get it to where it needs to be. This is also known as “prop drilling”, and can lead to some unwieldy code.

Vuex is the official state management solution for Vue. It works by having a central store for shared state, and providing methods to allow any component in your application to access that state. In essence, Vuex ensures your views remain consistent with your application data, regardless of which function triggers a change to your application data.

In this article, I’ll offer you a high-level overview of Vuex and demonstrate how to implement it into a simple app.

A Shopping Cart Example

Let’s consider a real-world example to demonstrate the problem that Vuex solves.

When you go to a shopping site, you’ll usually have a list of products. Each product has an Add to Cart button and sometimes an Items Remaining label indicating the current stock or the maximum number of items you can order for the specified product. Each time a product is purchased, the current stock of that product is reduced. When this happens, the Items Remaining label should update with the correct figure. When the product’s stock level reaches 0, the label should read Out of Stock. In addition, the Add to Cart button should be disabled or hidden to ensure customers can’t order products that are currently not in inventory.

Now ask yourself how you’d implement this logic. It may be trickier than you think. And let me throw in a curve ball. You’ll need another function for updating stock records when new stock comes in. When the depleted product’s stock is updated, both the Items Remaining label and the Add to Cart button should be updated instantly to reflect the new state of the stock.

Depending on your programming prowess, your solution may start to look a bit like spaghetti. Now, let’s imagine your boss tells you to develop an API that allows third-party sites to sell the products directly from the warehouse. The API needs to ensure that the main shopping website remains in sync with the products’ stock levels. At this point you feel like pulling your hair out and demanding why you weren’t told to implement this earlier. You feel like all your hard work has gone to waste, as you’ll need to completely rework your code to cope with this new requirement.

This is where a state management pattern library can save you from such headaches. It will help you organize the code that handles your front-end data in a way that makes adding new requirements a breeze.

Prerequisites

Before we start, I’ll assume that you:

  • have a basic knowledge of Vue.js
  • are familiar with ES6 and ES7 language features

You’ll also need to have a recent version of Node.js that’s not older than version 6.0. At the time of writing, Node.js v10.13.0 (LTS) and npm version 6.4.1 are the most recent. If you don’t have a suitable version of Node installed on your system already, I recommend using a version manager.

Finally, you should have the most recent version of the Vue CLI installed:

npm install -g @vue/cli

Build a Counter Using Local State

In this section, we’re going to build a simple counter that keeps track of its state locally. Once we’re done, I’ll go over the fundamental concepts of Vuex, before looking at how to rewrite the counter app to use Vue’s official state management solution.

Getting Set Up

Let’s generate a new project using the CLI:

vue create vuex-counter

A wizard will open up to guide you through the project creation. Select Manually select features and ensure that you choose to install Vuex.

Next, change into the new directory and in the src/components folder, rename HelloWorld.vue to Counter.vue:

cd vuex-counter
mv src/components/HelloWorld.vue src/components/Counter.vue

Finally, open up src/App.vue and replace the existing code with the following:

<template>
  <div id="app">
    <h1>Vuex Counter</h1>
    <Counter/>
  </div>
</template>

<script>
import Counter from './components/Counter.vue'

export default {
  name: 'app',
  components: {
    Counter
  }
}
</script>

You can leave the styles as they are.

Creating the Counter

Let’s start off by initializing a count and outputting it to the page. We’ll also inform the user whether the count is currently even or odd. Open up src/components/Counter.vue and replace the code with the following:

<template>
  <div>
    <p>Clicked {{ count }} times! Count is {{ parity }}.</p>
  </div>
</template>

<script>
export default {
  name: 'Counter',
  data: function() {
    return {
      count: 0
    };
  },
  computed: {
    parity: function() {
      return this.count % 2 === 0 ? 'even' : 'odd';
    }
  }
}
</script>

As you can see, we have one state variable called count and a computed function called parity which returns the string even or odd depending on the whether count is an odd or even number.

To see what we’ve got so far, start the app from within the root folder by running npm run serve and navigate to http://localhost:8080.

Feel free to change the value of the counter to show that the correct output for both counter and parity is displayed. When you’re satisfied, make sure to reset it back to 0 before we proceed to the next step.

Incrementing and Decrementing

Right after the computed property in the <script> section of Counter.vue, add this code:

methods: {
  increment: function () {
    this.count++;
  },
  decrement: function () {
    this.count--;
  },
  incrementIfOdd: function () {
    if (this.parity === 'odd') {
      this.increment();
    }
  },
  incrementAsync: function () {
    setTimeout(() => {
      this.increment()
    }, 1000)
  }
}

The first two functions, increment and decrement, are hopefully self-explanatory. The incrementIfOdd function only executes if the value of count is an odd number, whereas incrementAsync is an asynchronous function that performs an increment after one second.

In order to access these new methods from the template, we’ll need to define some buttons. Insert the following after the template code which outputs the count and parity:

<button @click="increment" variant="success">Increment</button>
<button @click="decrement" variant="danger">Decrement</button>
<button @click="incrementIfOdd" variant="info">Increment if Odd</button>
<button @click="incrementAsync" variant="warning">Increment Async</button>

After you’ve saved, the browser should refresh automatically. Click all of the buttons to ensure everything is working as expected. This is what you should have ended up with:

See the Pen Vue Counter Using Local State by SitePoint (@SitePoint) on CodePen.

The counter example is now complete. Let’s move and examine the fundamentals of Vuex, before looking at how we would rewrite the counter to implement them.

How Vuex Works

Before we go over the practical implementation, it’s best that we acquire a basic grasp of how Vuex code is organized. If you’re familiar with similar frameworks such as Redux, you shouldn’t find anything too surprising here. If you haven’t dealt with any Flux-based state management frameworks before, please pay close attention.

The Vuex Store

The store provides a centralized repository for shared state in Vue apps. This is what it looks like in its most basic form:

// src/store/index.js

import Vue from 'vue'
import Vuex from 'vuex'

Vue.use(Vuex)

export default new Vuex.Store({
  state: {
    // put variables and collections here
  },
  mutations: {
    // put sychronous functions for changing state e.g. add, edit, delete
  },
  actions: {
    // put asynchronous functions that can call one or more mutation functions
  }
})

After defining your store, you need to inject it into your Vue.js application like this:

// src/main.js
import store from './store'

new Vue({
  store,
  render: h => h(App)
}).$mount('#app')

This will make the injected store instance available to every component in our application as this.$store.

Working with State

Also referred to as the single state tree, this is simply an object that contains all front-end application data. Vuex, just like Redux, operates using a single store. Application data is organized in a tree-like structure. Its construction is quite simple. Here’s an example:

state: {
  products: [],
  count: 5,
  loggedInUser: {
    name: 'John',
    role: 'Admin'
  }
}

Here we have products that we’ve initialized with an empty array, and count, which is initialized with the value 5. We also have loggedInUser, which is a JavaScript object literal containing multiple fields. State properties can contain any valid datatype from Booleans, to arrays, to other objects.

There are multiple ways to display state in our views. We can reference the store directly in our templates using $store:

<template>
  <p>{{ $store.state.count }}</p>
</template>

Or we can return some store state from within a computed property:

<template>
  <p>{{ count }}</p>
</template>

<script>
export default {
  computed: {
    count() {
      return this.$store.state.count;
    }
  }
}
</script>

Since Vuex stores are reactive, whenever the value of $store.state.count changes, the view will change as well. All this happens behind the scenes, making your code look simple and cleaner.

The mapState Helper

Now, suppose you have multiple states you want to display in your views. Declaring a long list of computed properties can get verbose, so Vuex provides a mapState helper. This can be used to generate multiple computed properties easily. Here’s an example:

<template>
  <div>
    <p>Welcome, {{ loggedInUser.name }}.</p>
    <p>Count is {{ count }}.</p>
  </div>
</template>

<script>
import { mapState } from 'vuex';

export default {
  computed: mapState({
    count: state => state.count,
    loggedInUser: state => state.loggedInUser
  })
}
</script>

Here’s an even simpler alternative where we can pass an array of strings to the mapState helper function:

export default {
  computed: mapState([
    'count', 'loggedInUser'
  ])
}

This version of the code and the one above it do exactly the same thing. You should note that mapState returns an object. If you want to use it with other computed properties, you can use the spread operator. Here’s how:

computed: {
  ...mapState([
    'count', 'loggedInUser'
  ]),
  parity: function() {
    return this.count % 2  === 0 ? 'even' : 'odd'
  }
}

Getters

In a Vuex store, getters are the equivalent to Vue’s computed properties. They allow you to create derived state that can be shared between different components. Here’s a quick example:

getters: {
  depletedProducts: state => {
    return state.products.filter(product => product.stock <= 0)
  }
}

Results of getter handlers (when accessed as properties) are cached and can be called as many times as you wish. They’re also reactive to state changes. In other words, if the state it depends upon changes, the getter function is automatically executed and the new result is cached. Any component that has accessed a getter handler will get updated instantly. This is how you can access a getter handler from a component:

computed: {
  depletedProducts() {
    return this.$store.getters.depletedProducts;
  }
}

The mapGetters Helper

You can simplify the getters code by using the mapGetters helper:

import { mapGetters } from 'vuex'

export default {
  //..
  computed: {
    ...mapGetters([
      'depletedProducts',
      'anotherGetter'
    ])
  }
}

There’s an option for passing arguments to a getter handler by returning a function. This is useful if you want to perform a query within the getter:

getters: {
  getProductById: state => id => {
    return state.products.find(product => product.id === id);
  }
}

store.getters.getProductById(5)

Do note that each time a getter handler is accessed via a method, it will always run and the result won’t be cached.

Compare:

// property notation, result cached
store.getters.depletedProducts

// method notation, result not cached
store.getters.getProductById(5)

Changing State with Mutations

An important aspect of the Vuex architecture is that components never alter the state directly. Doing so can lead to odd bugs and inconsistencies in the app’s state.

Instead, the way to change state in a Vuex store is by committing a mutation. For those of you familiar with Redux, these are similar to reducers.

Here is an example of a mutation that increases a count variable stored in state:

export default new Vuex.Store({
  state:{
    count: 1
  },
  mutations: {
    increment(state) {
      state.count++
    }
  }
})

You can’t call a mutation handler directly. Instead, you trigger one by “committing a mutation” like this:

methods: {
  updateCount() {
    this.$store.commit('increment');
  }
}

You can also pass parameters to a mutation:

// store.js
mutations: {
  incrementBy(state, n) {
    state.count += n;
  }
}

// component
updateCount() {
  this.$store.commit('incrementBy', 25);
}

In the above example, we’re passing the mutation an integer by which it should increase the count. You can also pass an object as a parameter. This way, you can include multiple fields easily without overloading your mutation handler:

// store.js
mutations: {
  incrementBy(state, payload) {
    state.count += payload.amount;
  }
}

// component
updateCount() {
  this.$store.commit('incrementBy', { amount: 25 });
}

You can also perform an object-style commit that looks like this:

store.commit({
  type: 'incrementBy',
  amount: 25
})

The mutation handler will remain the same.

The mapMutations Helper

Similar to mapState and mapGetters, you can also use the mapMutations helper to reduce the boilerplate for your mutation handlers:

import { mapMutations } from  'vuex'

export default{
  methods: {
    ...mapMutations([
      'increment', // maps to this.increment()
      'incrementBy' // maps to this.incrementBy(amount)
    ])
  }
}

On a final note, mutation handlers must be synchronous. You can attempt to write an asynchronous mutation function, but you’ll come to find out later down the road that it causes unnecessary complications. Let’s move on to actions.

Actions

Actions are functions that don’t change the state themselves. Instead, they commit mutations after performing some logic (which is often asynchronous). Here’s a simple example of an action:

//..
actions: {
  increment(context) {
    context.commit('increment');
  }
}

Action handlers receive a context object as their first argument, which gives us access to store properties and methods. For example:

  • context.commit: commit a mutation
  • context.state: access state
  • context.getters: access getters

You can also use argument destructing to extract the store attributes you need for your code. For example:

actions: {
  increment({ commit }) {
    commit('increment');
  }
}

As mentioned above, actions can be asynchronous. Here’s an example:

actions: {
  incrementAsync: async({ commit }) => {
    return await setTimeout(() => { commit('increment') }, 1000);
  }
}

In this example, the mutation is committed after 1,000 milliseconds.

Like mutations, action handlers aren’t called directly, but rather via a dedicated dispatch method on the store, like so:

store.dispatch('incrementAsync')

// dispatch with payload
store.dispatch('incrementBy', { amount: 25})

// dispatch with object
store.dispatch({
  type: 'incrementBy',
  amount: 25
})

You can dispatch an action in a component like this:

this.$store.dispatch('increment')

The mapActions Helper

Alternatively, you can use the mapActions helper to assign action handlers to local methods:

import { mapActions } from  'vuex'

export default {
  //..
  methods: {
    ...mapActions([
      'incrementBy', // maps this.increment(amount) to this.$store.dispatch(increment)
      'incrementAsync', // maps this.incrementAsync() to this.$store.dispatch(incrementAsync)
      add: 'increment' // maps this.add() to this.$store.dispatch(increment)
    ])
  }
}

Re-build Counter App Using Vuex

Now that we’ve had a look at the core concepts of Vuex, it’s time to implement what we’ve learned and rewrite our counter to make use of Vue’s official state management solution.

If you fancy a challenge, you might like to have a go at doing this yourself before reading on …

When we generated our project using Vue CLI, we selected Vuex as one of the features. A couple of things happened:

  1. Vuex was installed as a package dependency. Check your package.json to confirm this.
  2. A store.js file was created and injected into your Vue.js application via main.js.

To convert our “local state” counter app to a Vuex application, open src/store.js and update the code as follows:

import Vue from 'vue'
import Vuex from 'vuex'

Vue.use(Vuex)

export default new Vuex.Store({
  state: {
    count: 0
  },
  getters: {
    parity: state => state.count % 2 === 0 ? 'even' : 'odd'
  },
  mutations: {
    increment(state) {
      state.count++;
    },
    decrement(state) {
      state.count--;
    }
  },
  actions: {
    increment: ({ commit }) => commit('increment'),
    decrement: ({ commit }) => commit('decrement'),
    incrementIfOdd: ({ commit, getters }) => getters.parity === 'odd' ? commit('increment') : false,
    incrementAsync: ({ commit }) => {
      setTimeout(() => { commit('increment') }, 1000);
    }
  }
});

Here we can see how a complete Vuex store is structured in practice. Please go back over the theory part of this article if anything here is unclear to you.

Next, update the src/components/Counter.vue component by replacing the existing code within the <script> block. We’ll switch the local state and functions to the newly created ones in the Vuex store:

import { mapState mapGetters, mapActions } from 'vuex'

export default {
  name: 'Counter',
  computed: {
    ...mapState([
      'count'
    ]),
    ...mapGetters([
      'parity'
    ])
  },
  methods: mapActions([
    'increment',
    'decrement',
    'incrementIfOdd',
    'incrementAsync'
  ])
}

The template code should remain the same, as we’re sticking to the previous variable and function names. See how much cleaner the code now is.

If you don’t want to use the state and getter map helpers, you can access the store data directly from your template like this:

<p>
  Clicked {{ $store.state.count }} times! Count is {{ $store.getters.parity }}.
</p>

After you’ve saved your changes, make sure to test your application. From an end-user perspective, the counter application should function exactly the same as before. The only difference is that the counter is now operating from a Vuex store.

See the Pen Vue Counter Using Vuex by SitePoint (@SitePoint) on CodePen.

Conclusion

In this article, we’ve looked at what Vuex is, what problem it solves, how to install it, as well as its core concepts. We then applied these concepts to refactor our counter app to work with Vuex. Hopefully this introduction will serve you well in implementing Vuex in your own projects.

How to build Vue.js JWT Authentication with Vuex and Vue Router

How to build Vue.js JWT Authentication with Vuex and Vue Router

In this tutorial, we’re gonna build a Vue.js with Vuex and Vue Router Application that supports JWT Authentication

In this tutorial, we’re gonna build a Vue.js with Vuex and Vue Router Application that supports JWT Authentication. I will show you:

  • JWT Authentication Flow for User Signup & User Login
  • Project Structure for Vue.js Authentication with Vuex & Vue Router
  • How to define Vuex Authentication module
  • Creating Vue Authentication Components with Vuex Store & VeeValidate
  • Vue Components for accessing protected Resources
  • How to add a dynamic Navigation Bar to Vue App

Let’s explore together.

Contents

Overview of Vue JWT Authentication example

We will build a Vue application in that:

  • There are Login/Logout, Signup pages.
  • Form data will be validated by front-end before being sent to back-end.
  • Depending on User’s roles (admin, moderator, user), Navigation Bar changes its items automatically.

Screenshots

– Signup Page:

– Login Page & Profile Page (for successful Login):

– Navigation Bar for Admin account:

Demo

This is full Vue JWT Authentication App demo (with form validation, check signup username/email duplicates, test authorization with 3 roles: Admin, Moderator, User). In the video, we use Spring Boot for back-end REST APIs.

Flow for User Registration and User Login

For JWT Authentication, we’re gonna call 2 endpoints:

  • POST api/auth/signup for User Registration
  • POST api/auth/signin for User Login

You can take a look at following flow to have an overview of Requests and Responses Vue Client will make or receive.

Vue Client must add a JWT to HTTP Authorization Header before sending request to protected resources.

Vue App Component Diagram with Vuex & Vue Router

Now look at the diagram below.

Let’s think about it.

– The App component is a container with Router. It gets app state from Vuex store/auth. Then the navbar now can display based on the state. App component also passes state to its child components.

Login & Register components have form for submission data (with support of vee-validate). We call Vuex store dispatch() function to make login/register actions.

– Our Vuex actions call auth.service methods which use axios to make HTTP requests. We also store or get JWT from Browser Local Storage inside these methods.

Home component is public for all visitor.

Profile component get user data from its parent component and display user information.

BoardUser, BoardModerator, BoardAdmin components will be displayed by Vuex state user.roles. In these components, we use user.service to get protected resources from API.

user.service uses auth-header() helper function to add JWT to HTTP Authorization header. auth-header() returns an object containing the JWT of the currently logged in user from Local Storage.

Technology

We will use these modules:

  • vue: 2.6.10
  • vue-router: 3.0.3
  • vuex: 3.0.1
  • axios: 0.19.0
  • vee-validate: 2.2.15
  • bootstrap: 4.3.1
  • vue-fontawesome: 0.1.7
Project Structure

This is folders & files structure for our Vue application:

With the explaination in diagram above, you can understand the project structure easily.

Setup Vue App modules

Run following command to install neccessary modules:

npm install vue-router
npm install vuex
npm install [email protected]
npm install axios
npm install bootstrap jquery popper.js
npm install @fortawesome/fontawesome-svg-core @fortawesome/free-solid-svg-icons @fortawesome/vue-fontawesome

After the installation is done, you can check dependencies in package.json file.

"dependencies": {
  "@fortawesome/fontawesome-svg-core": "^1.2.25",
  "@fortawesome/free-solid-svg-icons": "^5.11.2",
  "@fortawesome/vue-fontawesome": "^0.1.7",
  "axios": "^0.19.0",
  "bootstrap": "^4.3.1",
  "core-js": "^2.6.5",
  "jquery": "^3.4.1",
  "popper.js": "^1.15.0",
  "vee-validate": "^2.2.15",
  "vue": "^2.6.10",
  "vue-router": "^3.0.3",
  "vuex": "^3.0.1"
},

Open src/main.js, add code below:

import Vue from 'vue';
import App from './App.vue';
import { router } from './router';
import store from './store';
import 'bootstrap';
import 'bootstrap/dist/css/bootstrap.min.css';
import VeeValidate from 'vee-validate';
import { library } from '@fortawesome/fontawesome-svg-core';
import { FontAwesomeIcon } from '@fortawesome/vue-fontawesome';
import {
  faHome,
  faUser,
  faUserPlus,
  faSignInAlt,
  faSignOutAlt
} from '@fortawesome/free-solid-svg-icons';

library.add(faHome, faUser, faUserPlus, faSignInAlt, faSignOutAlt);

Vue.config.productionTip = false;

Vue.use(VeeValidate);
Vue.component('font-awesome-icon', FontAwesomeIcon);

new Vue({
  router,
  store,
  render: h => h(App)
}).$mount('#app');

You can see that we import and apply in Vue object:
store for Vuex (implemented later in src/store)
router for Vue Router (implemented later in src/router.js)
bootstrap with CSS
vee-validate
vue-fontawesome for icons (used later in nav)

Create Services

We create two services in src/services folder:


services

auth-header.js

auth.service.js (Authentication service)

user.service.js (Data service)


Authentication service

The service provides three important methods with the help of axios for HTTP requests & reponses:

  • login(): POST {username, password} & save JWT to Local Storage
  • logout(): remove JWT from Local Storage
  • register(): POST {username, email, password}
import axios from 'axios';

const API_URL = 'http://localhost:8080/api/auth/';

class AuthService {
  login(user) {
    return axios
      .post(API_URL + 'signin', {
        username: user.username,
        password: user.password
      })
      .then(this.handleResponse)
      .then(response => {
        if (response.data.accessToken) {
          localStorage.setItem('user', JSON.stringify(response.data));
        }

        return response.data;
      });
  }

  logout() {
    localStorage.removeItem('user');
  }

  register(user) {
    return axios.post(API_URL + 'signup', {
      username: user.username,
      email: user.email,
      password: user.password
    });
  }

  handleResponse(response) {
    if (response.status === 401) {
      this.logout();
      location.reload(true);

      const error = response.data && response.data.message;
      return Promise.reject(error);
    }

    return Promise.resolve(response);
  }
}

export default new AuthService();

If login request returns 401 status (Unauthorized), that means, JWT was expired or no longer valid, we will logout the user (remove JWT from Local Storage).

Data service

We also have methods for retrieving data from server. In the case we access protected resources, the HTTP request needs Authorization header.

Let’s create a helper function called authHeader() inside auth-header.js:

export default function authHeader() {
  let user = JSON.parse(localStorage.getItem('user'));

  if (user && user.accessToken) {
    return { Authorization: 'Bearer ' + user.accessToken };
  } else {
    return {};
  }
}

It checks Local Storage for user item.
If there is a logged in user with accessToken (JWT), return HTTP Authorization header. Otherwise, return an empty object.

Now we define a service for accessing data in user.service.js:

import axios from 'axios';
import authHeader from './auth-header';

const API_URL = 'http://localhost:8080/api/test/';

class UserService {
  getPublicContent() {
    return axios.get(API_URL + 'all');
  }

  getUserBoard() {
    return axios.get(API_URL + 'user', { headers: authHeader() });
  }

  getModeratorBoard() {
    return axios.get(API_URL + 'mod', { headers: authHeader() });
  }

  getAdminBoard() {
    return axios.get(API_URL + 'admin', { headers: authHeader() });
  }
}

export default new UserService();

You can see that we add a HTTP header with the help of authHeader() function when requesting authorized resource.

Define Vuex Authentication module

We put Vuex module for authentication in src/store folder.


store

auth.module.js (authentication module)

index.js (Vuex Store that contains also modules)


Now open index.js file, import auth.module to main Vuex Store here.

import Vue from 'vue';
import Vuex from 'vuex';

import { auth } from './auth.module';

Vue.use(Vuex);

export default new Vuex.Store({
  modules: {
    auth
  }
});

Then we start to define Vuex Authentication module that contains:

  • state: { status, user }
  • actions: { login, logout, register }
  • mutations: { loginSuccess, loginFailure, logout, registerSuccess, registerFailure }

We use AuthService which is defined above to make authentication requests.

auth.module.js

import AuthService from '../services/auth.service';

const user = JSON.parse(localStorage.getItem('user'));
const initialState = user
  ? { status: { loggedIn: true }, user }
  : { status: {}, user: null };

export const auth = {
  namespaced: true,
  state: initialState,
  actions: {
    login({ commit }, user) {
      return AuthService.login(user).then(
        user => {
          commit('loginSuccess', user);
          return Promise.resolve(user);
        },
        error => {
          commit('loginFailure');
          return Promise.reject(error.response.data);
        }
      );
    },
    logout({ commit }) {
      AuthService.logout();
      commit('logout');
    },
    register({ commit }, user) {
      return AuthService.register(user).then(
        response => {
          commit('registerSuccess');
          return Promise.resolve(response.data);
        },
        error => {
          commit('registerFailure');
          return Promise.reject(error.response.data);
        }
      );
    }
  },
  mutations: {
    loginSuccess(state, user) {
      state.status = { loggedIn: true };
      state.user = user;
    },
    loginFailure(state) {
      state.status = {};
      state.user = null;
    },
    logout(state) {
      state.status = {};
      state.user = null;
    },
    registerSuccess(state) {
      state.status = {};
    },
    registerFailure(state) {
      state.status = {};
    }
  }
};

You can find more details about Vuex at Vuex Guide.

Create Vue Authentication Components

Define User model

To make code clear and easy to read, we define the User model first.
Under src/models folder, create user.js like this.

export default class User {
  constructor(username, email, password) {
    this.username = username;
    this.email = email;
    this.password = password;
  }
}

Let’s continue with Authentication Components.
Instead of using axios or AuthService directly, these Components should work with Vuex Store:
– getting status with this.$store.state.auth
– making request by dispatching an action: this.$store.dispatch()


views

Login.vue

Register.vue

Profile.vue


Vue Login Page

In src/views folder, create Login.vue file with following code:

<template>
  <div class="col-md-12">
    <div class="card card-container">
      <img
        id="profile-img"
        src="//ssl.gstatic.com/accounts/ui/avatar_2x.png"
        class="profile-img-card"
      />
      <form name="form" @submit.prevent="handleLogin">
        <div class="form-group">
          <label for="username">Username</label>
          <input
            type="text"
            class="form-control"
            name="username"
            v-model="user.username"
            v-validate="'required'"
          />
          <div
            class="alert alert-danger"
            role="alert"
            v-if="errors.has('username')"
          >Username is required!</div>
        </div>
        <div class="form-group">
          <label for="password">Password</label>
          <input
            type="password"
            class="form-control"
            name="password"
            v-model="user.password"
            v-validate="'required'"
          />
          <div
            class="alert alert-danger"
            role="alert"
            v-if="errors.has('password')"
          >Password is required!</div>
        </div>
        <div class="form-group">
          <button class="btn btn-primary btn-block" :disabled="loading">
            <span class="spinner-border spinner-border-sm" v-show="loading"></span>
            <span>Login</span>
          </button>
        </div>
        <div class="form-group">
          <div class="alert alert-danger" role="alert" v-if="message">{{message}}</div>
        </div>
      </form>
    </div>
  </div>
</template>

<script>
import User from '../models/user';

export default {
  name: 'login',
  computed: {
    loggedIn() {
      return this.$store.state.auth.status.loggedIn;
    }
  },
  data() {
    return {
      user: new User('', ''),
      loading: false,
      message: ''
    };
  },
  mounted() {
    if (this.loggedIn) {
      this.$router.push('/profile');
    }
  },
  methods: {
    handleLogin() {
      this.loading = true;
      this.$validator.validateAll();

      if (this.errors.any()) {
        this.loading = false;
        return;
      }

      if (this.user.username && this.user.password) {
        this.$store.dispatch('auth/login', this.user).then(
          () => {
            this.$router.push('/profile');
          },
          error => {
            this.loading = false;
            this.message = error.message;
          }
        );
      }
    }
  }
};
</script>

<style scoped>
label {
  display: block;
  margin-top: 10px;
}

.card-container.card {
  max-width: 350px !important;
  padding: 40px 40px;
}

.card {
  background-color: #f7f7f7;
  padding: 20px 25px 30px;
  margin: 0 auto 25px;
  margin-top: 50px;
  -moz-border-radius: 2px;
  -webkit-border-radius: 2px;
  border-radius: 2px;
  -moz-box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.3);
  -webkit-box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.3);
  box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.3);
}

.profile-img-card {
  width: 96px;
  height: 96px;
  margin: 0 auto 10px;
  display: block;
  -moz-border-radius: 50%;
  -webkit-border-radius: 50%;
  border-radius: 50%;
}
</style>

This page has a Form with username & password. We use [VeeValidate 2.x](http://<a href=) to validate input before submitting the form. If there is an invalid field, we show the error message.

We check user logged in status using Vuex Store: this.$store.state.auth.status.loggedIn. If the status is true, we use Vue Router to direct user to Profile Page:

created() {
  if (this.loggedIn) {
    this.$router.push('/profile');
  }
},

In the handleLogin() function, we dispatch 'auth/login' Action to Vuex Store. If the login is successful, go to Profile Page, otherwise, show error message.

Vue Register Page

This page is similar to Login Page.

For form validation, we have some more details:

  • username: required|min:3|max:20
  • email: required|email|max:50
  • password: required|min:6|max:40

For form submission, we dispatch 'auth/register' Vuex Action.

src/views/Register.vue

<template>
  <div class="col-md-12">
    <div class="card card-container">
      <img
        id="profile-img"
        src="//ssl.gstatic.com/accounts/ui/avatar_2x.png"
        class="profile-img-card"
      />
      <form name="form" @submit.prevent="handleRegister">
        <div v-if="!successful">
          <div class="form-group">
            <label for="username">Username</label>
            <input
              type="text"
              class="form-control"
              name="username"
              v-model="user.username"
              v-validate="'required|min:3|max:20'"
            />
            <div
              class="alert-danger"
              v-if="submitted && errors.has('username')"
            >{{errors.first('username')}}</div>
          </div>
          <div class="form-group">
            <label for="email">Email</label>
            <input
              type="email"
              class="form-control"
              name="email"
              v-model="user.email"
              v-validate="'required|email|max:50'"
            />
            <div
              class="alert-danger"
              v-if="submitted && errors.has('email')"
            >{{errors.first('email')}}</div>
          </div>
          <div class="form-group">
            <label for="password">Password</label>
            <input
              type="password"
              class="form-control"
              name="password"
              v-model="user.password"
              v-validate="'required|min:6|max:40'"
            />
            <div
              class="alert-danger"
              v-if="submitted && errors.has('password')"
            >{{errors.first('password')}}</div>
          </div>
          <div class="form-group">
            <button class="btn btn-primary btn-block">Sign Up</button>
          </div>
        </div>
      </form>

      <div
        class="alert"
        :class="successful ? 'alert-success' : 'alert-danger'"
        v-if="message"
      >{{message}}</div>
    </div>
  </div>
</template>

<script>
import User from '../models/user';

export default {
  name: 'register',
  computed: {
    loggedIn() {
      return this.$store.state.auth.status.loggedIn;
    }
  },
  data() {
    return {
      user: new User('', '', ''),
      submitted: false,
      successful: false,
      message: ''
    };
  },
  mounted() {
    if (this.loggedIn) {
      this.$router.push('/profile');
    }
  },
  methods: {
    handleRegister() {
      this.message = '';
      this.submitted = true;
      this.$validator.validate().then(valid => {
        if (valid) {
          this.$store.dispatch('auth/register', this.user).then(
            data => {
              this.message = data.message;
              this.successful = true;
            },
            error => {
              this.message = error.message;
              this.successful = false;
            }
          );
        }
      });
    }
  }
};
</script>

<style scoped>
label {
  display: block;
  margin-top: 10px;
}

.card-container.card {
  max-width: 350px !important;
  padding: 40px 40px;
}

.card {
  background-color: #f7f7f7;
  padding: 20px 25px 30px;
  margin: 0 auto 25px;
  margin-top: 50px;
  -moz-border-radius: 2px;
  -webkit-border-radius: 2px;
  border-radius: 2px;
  -moz-box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.3);
  -webkit-box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.3);
  box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.3);
}

.profile-img-card {
  width: 96px;
  height: 96px;
  margin: 0 auto 10px;
  display: block;
  -moz-border-radius: 50%;
  -webkit-border-radius: 50%;
  border-radius: 50%;
}
</style>

Profile Page

This page gets current User from Vuex Store and show information. If the User is not logged in, it directs to Login Page.

src/views/Profile.vue

<template>
  <div class="container">
    <header class="jumbotron">
      <h3>
        <strong>{{currentUser.username}}</strong> Profile
      </h3>
    </header>
    <p>
      <strong>Token:</strong>
      {{currentUser.accessToken.substring(0, 20)}} ... {{currentUser.accessToken.substr(currentUser.accessToken.length - 20)}}
    </p>
    <p>
      <strong>Id:</strong>
      {{currentUser.id}}
    </p>
    <p>
      <strong>Email:</strong>
      {{currentUser.email}}
    </p>
    <strong>Authorities:</strong>
    <ul>
      <li v-for="(role,index) in currentUser.roles" :key="index">{{role}}</li>
    </ul>
  </div>
</template>

<script>
export default {
  name: 'profile',
  computed: {
    currentUser() {
      return this.$store.state.auth.user;
    }
  },
  mounted() {
    if (!this.currentUser) {
      this.$router.push('/login');
    }
  }
};
</script>

Create Vue Components for accessing Resources

These components will use UserService to request data.


views

Home.vue

BoardAdmin.vue

BoardModerator.vue

BoardUser.vue


Home Page

This is a public page.

src/views/Home.vue

<template>
  <div class="container">
    <header class="jumbotron">
      <h3>{{content}}</h3>
    </header>
  </div>
</template>

<script>
import UserService from '../services/user.service';

export default {
  name: 'home',
  data() {
    return {
      content: ''
    };
  },
  mounted() {
    UserService.getPublicContent().then(
      response => {
        this.content = response.data;
      },
      error => {
        this.content = error.response.data.message;
      }
    );
  }
};
</script>

Role-based Pages

We have 3 pages for accessing protected data:

  • BoardUser page calls UserService.getUserBoard()
  • BoardModerator page calls UserService.getModeratorBoard()
  • BoardAdmin page calls UserService.getAdminBoard()

This is an example, other Page are similar to this Page.

src/views/BoardUser.vue

<template>
  <div class="container">
    <header class="jumbotron">
      <h3>{{content}}</h3>
    </header>
  </div>
</template>

<script>
import UserService from '../services/user.service';

export default {
  name: 'user',
  data() {
    return {
      content: ''
    };
  },
  mounted() {
    UserService.getUserBoard().then(
      response => {
        this.content = response.data;
      },
      error => {
        this.content = error.response.data.message;
      }
    );
  }
};
</script>

Define Routes for Vue Router

Now we define all routes for our Vue Application.

src/router.js

import Vue from 'vue';
import Router from 'vue-router';
import Home from './views/Home.vue';
import Login from './views/Login.vue';
import Register from './views/Register.vue';

Vue.use(Router);

export const router = new Router({
  mode: 'history',
  routes: [
    {
      path: '/',
      name: 'home',
      component: Home
    },
    {
      path: '/home',
      component: Home
    },
    {
      path: '/login',
      component: Login
    },
    {
      path: '/register',
      component: Register
    },
    {
      path: '/profile',
      name: 'profile',
      // lazy-loaded
      component: () => import('./views/Profile.vue')
    },
    {
      path: '/admin',
      name: 'admin',
      // lazy-loaded
      component: () => import('./views/BoardAdmin.vue')
    },
    {
      path: '/mod',
      name: 'moderator',
      // lazy-loaded
      component: () => import('./views/BoardModerator.vue')
    },
    {
      path: '/user',
      name: 'user',
      // lazy-loaded
      component: () => import('./views/BoardUser.vue')
    }
  ]
});

Add Navigation Bar to Vue App

This is the root container for our application that contains navigation bar. We will add router-view here.

src/App.vue

<template>
  <div id="app">
    <nav class="navbar navbar-expand navbar-dark bg-dark">
      <a href="#" class="navbar-brand">bezKoder</a>
      <div class="navbar-nav mr-auto">
        <li class="nav-item">
          <a href="/home" class="nav-link">
            <font-awesome-icon icon="home" /> Home
          </a>
        </li>
        <li class="nav-item" v-if="showAdminBoard">
          <a href="/admin" class="nav-link">Admin Board</a>
        </li>
        <li class="nav-item" v-if="showModeratorBoard">
          <a href="/mod" class="nav-link">Moderator Board</a>
        </li>
        <li class="nav-item">
          <a href="/user" class="nav-link" v-if="currentUser">User</a>
        </li>
      </div>

      <div class="navbar-nav ml-auto" v-if="!currentUser">
        <li class="nav-item">
          <a href="/register" class="nav-link">
            <font-awesome-icon icon="user-plus" /> Sign Up
          </a>
        </li>
        <li class="nav-item">
          <a href="/login" class="nav-link">
            <font-awesome-icon icon="sign-in-alt" /> Login
          </a>
        </li>
      </div>

      <div class="navbar-nav ml-auto" v-if="currentUser">
        <li class="nav-item">
          <a href="/profile" class="nav-link">
            <font-awesome-icon icon="user" />
            {{currentUser.username}}
          </a>
        </li>
        <li class="nav-item">
          <a href class="nav-link" @click="logOut">
            <font-awesome-icon icon="sign-out-alt" /> LogOut
          </a>
        </li>
      </div>
    </nav>

    <div class="container">
      <router-view />
    </div>
  </div>
</template>

<script>
export default {
  computed: {
    currentUser() {
      return this.$store.state.auth.user;
    },
    showAdminBoard() {
      if (this.currentUser) {
        return this.currentUser.roles.includes('ROLE_ADMIN');
      }

      return false;
    },
    showModeratorBoard() {
      if (this.currentUser) {
        return this.currentUser.roles.includes('ROLE_MODERATOR');
      }

      return false;
    }
  },
  methods: {
    logOut() {
      this.$store.dispatch('auth/logout');
      this.$router.push('/login');
    }
  }
};
</script>

Our navbar looks more professional when using font-awesome-icon.
We also make the navbar dynamically change by current User’s roles which are retrieved from Vuex Store state.

Handle Unauthorized Access

If you want to check Authorized status everytime a navigating action is trigger, just add router.beforeEach() at the end of src/router.js like this:

router.beforeEach((to, from, next) => {
  const publicPages = ['/login', '/home'];
  const authRequired = !publicPages.includes(to.path);
  const loggedIn = localStorage.getItem('user');

  // try to access a restricted page + not logged in
  if (authRequired && !loggedIn) {
    return next('/login');
  }

  next();
});

Conclusion

Congratulation!

Today we’ve done so many interesting things. I hope you understand the overall layers of our Vue application, and apply it in your project at ease. Now you can build a front-end app that supports JWT Authentication with Vue.js, Vuex and Vue Router.

Happy learning, see you again!

Performance Boost Using Highcharts.js and Vue.js

Performance Boost Using Highcharts.js and Vue.js

How to Maintain Performance with Big Datasets Using Highcharts. js and Vue. Sometimes you just need to show big datasets in your project. However, the library that you've used so far, as soon as you start to add data, becomes clunky and slow.

Sometimes you just need to show big datasets in your project. However, the library that you’ve used so far, as soon as you start to add data, becomes clunky and slow. You start to optimize your code, make cuts, or simplifications in datasets… In this article I’m going to show you that it does not have to be that way

Used by “80% of the largest companies in the world”, Highcharts is a powerful tool that allows you to plot massive series of data in a dynamic manner. As it’s free for non-commercial use, you can easily check for yourself if it’s going to suit your tastes. This project will also use highcharts-vue, which is a wrapper for Highcharts.

Installation:

The tools that we are going to need for the job are:

  • Highcharts
  • Highcharts vue
  • Axios

You can easily install them all at once using npm command:

npm i highcharts highcharts-vue axios -S

Now that we have all the pieces, let’s add them in the main.js file:

import Highcharts from "highcharts";
import HighchartsVue from "highcharts-vue";
import boost from "highcharts/modules/boost";

Vue.use(HighchartsVue);
boost(Highcharts);

You may be wondering, what this boost module is. I think that, to best explain it, the official documentation can be cited:

Boost is a stripped-down renderer-in-a-module for Highcharts and Highstock. It bypasses some of the standard Highcharts features (such as animation), and focuses on pushing as many points as possible as quickly as possible.

So, to sum it up, this module will make our charts run faster, but at the cost of some minor drawbacks. For example, you won’t be able to use dotted lines for your series. But, don’t you worry, the key parts are still fully functional.

Disclaimer: As the boost module is still in development, it can cause several bugs. For example, when using timestamps as x value, boost.useGPUTranslations will cause points to render in wrong places while zoomed, so you will need to do additional research, or just ask on the Highcharts forums.

Mocking the data:

As we need to have some data to show, and you probably don’t have any endpoints hanging around, we will need to generate some dummy data. We will need to create an object that has two (or more) attributes filled with chart data (for the sake of showing performance - about 100k points each, but you can totally try with 200-300k, or more). Highcharts allows us to add such as series in two ways:

  • array of {x,y} objects
  • array of values (where you specify the start of each series, as well as intervals)

This article covers how to make use of the first way, but you can always read the official Highcharts documentation to see other possibilities. To get the data, if you don’t want to generate it yourself, you can use my test.json (it’s in a public folder on the repo).

Let’s make use of it:

Now that we have some data to show, we can filtrate it. Even though this is a simplified version of the real application, we can create our architecture in a way that somewhat reflects the real case. Therefore, we can create 3 files:

  • ChartFiltration.vue
  • Chart.vue
  • store.js

ChartFiltration.vue will be, a parent of a Chart component. Its job will be issuing fetches and to know when the data is ready. Chart.vue will simply be used to show the series that are being passed by props. All logic related to processing the chart data will be stored in a store module.

First App.vue

<template>
  <div id="app">
    <ChartFiltration />
  </div>
</template>

<script>
import ChartFiltration from "./components/ChartFiltration";

export default {
  components: { ChartFiltration }
};
</script>

Nothing too fancy here, just some imports.

ChartFiltration.vue

<template>
  <div v-if="series">
    <Chart :series="series" />
  </div>
  <div v-else>
    Data is loading
  </div>
</template>

<script>
import { mapState } from "vuex";
import Chart from "./Chart";

export default {
  name: "ChartFiltration",
  components: { Chart },
  mounted() {
    this.$store.dispatch("fetchData");
  },
  computed: mapState({
    series: state => state.data
  })
};
</script>

As you can see, when the component is being mounted, the fetch in the store will be dispatched. The data will be mapped to a computed series. As I use conditional rendering, Chart.vue component will be rendered only when a series will have its length (because they will be returned as an array).

store.js

import Vue from "vue";
import Vuex from "vuex";
import axios from "axios";

Vue.use(Vuex);

const RESET_ERROR = null;
const generateSeries = data => {
  return Object.keys(data).map(attribute => {
    return {
      type: "line",
      boostThreshold: 1,
      turboThreshold: 0,
      animation: false,
      name: attribute,
      data: data[attribute],
      marker: { enabled: true, radius: 3 },
      states: { hover: { lineWidthPlus: 0 } }
    };
  });
};
export default new Vuex.Store({
  state: {
    data: null,
    error: null
  },
  mutations: {
    SET_DATA(state, data) {
      state.data = generateSeries(data);
    },
    SET_ERROR(state, error) {
      state.error = error;
    }
  },
  actions: {
    async fetchData({ commit }) {
      commit("SET_ERROR", RESET_ERROR);

      axios
        .get("/test.json")
        .then(res => {
          commit("SET_DATA", res.data);
        })
        .catch(err => {
          commit("SET_ERROR", err);
        });
    }
  }
});

In this article I simply want to show how to work with data in Highcharts. There is no need to use modules for the store, like we would in a real application and, therefore, this is why I will use a single store file. Let’s focus on fetchData action. I simulate the http call with axios. After the data has been “fetched”, we will commit the SET_DATA mutation. Highcharts has its specific way of building chart objects. Because there can’t be too much logic in mutations, we add an additional helper function to process our response properly.

const generateSeries = data => {
  return Object.keys(data).map(attribute => {
    return {
      type: "line",
      boostThreshold: 1,
      turboThreshold: 0,
      animation: false,
      name: attribute,
      data: data[attribute],
      marker: { enabled: true, radius: 3 },
      states: { hover: { lineWidthPlus: 0 } }
    };
  });
};

The helper function simply iterates on object to get its attributes. After each iteration, we return the Highcharts series object, and this is what we will focus on:

  • type: here you can specify a type of series
  • boostThreshold: point threshold for when a series should enter boost mode. 1 means that we always want to use boost, 0 means never
  • turboThreshold: for a bigger {x,y} series, it’s better to disable it (by setting 0) as it will not render. If the set threshold is passed, only one dimensional arrays of numbers, or two dimensional arrays with x and y values, are allowed
  • animation: as animations slow down our chart, we don’t want them
  • name: name of the series shown in the legend
  • data: here, we need to assign our array of datapoints
  • marker: size of the markers on the chart
  • states: here, we will disable the line thickening on hover, as it will add lag for big datasets

What can we set additionally ?

  • color: remember that, when using the boost module, you can only use simple colors (rgb/hex). You can also set them with css, but it’s trickier.
  • Honestly, whatever you want, as this is a simple object that you will have access to by using this keyword in the chart object (for example, in the tooltip formatter). You can add units for series, or another type of name to show, but remember that you will need to handle logic for those by yourself.

Here is a list of attributes that you can officially assign for a series.

Now that we have our data processed, we can focus on showing it.

Chart.vue

<template>
  <highcharts :options="chartOptions" />
</template>
<script>
export default {
  name: "Chart",
  props: {
    series: { type: Array, required: true }
  },
  computed: {
    chartOptions() {
      return {
        chart: {
          type: "line",
          height: "700px",
          redraw: true,
          animation: false,
          zoomType: "xy",
          panning: true,
          panKey: "shift"
        },
        boost: { enabled: true },
        tooltip: {
          formatter() {
            const time = new Date(this.x).toJSON();
            const name = this.series.name;
            return `<b>${name}</b><br />
              value: ${this.y} <br />
              time: ${time}`;
          }
        },
        series: this.series,
        xAxis: {
          type: "datetime"
        }
      };
    }
  }
};
</script>

This components sole function is to create a chartOptions object that is passed to the highcharts-vue wrapper. We pass the series as props. On each change, a new chartOptions object will be computed and will force the whole component to rerender. Let’s look at the function that creates it:

chartOptions() {
      return {
        chart: {
          type: "line",
          height: "700px",
          animation: false,
          zoomType: "xy",
          panning: true,
          panKey: "shift"
        },
        boost: { enabled: true },
        tooltip: {
          formatter() {
            const time = new Date(this.x).toJSON();
            const name = this.series.name;
            return `<b>${name}</b><br />
              value: ${this.y} <br />
              time: ${time}`;
          }
        },
        series: this.series,
        xAxis: {
          type: "datetime"
        }
      };
    }

  • chart: has basic information about chart.
    • type: specifies which type of chart we are going to show
    • height: we can simply specify how much height in px this chart is going to have
    • animation: disables all animations which may slow down the chart
    • zoomType: specifies what type of zoom we can use. ‘xy’ means that we can zoom in both directions
    • panning: true allows us to pan the chart after zooming
    • panKey: specifies which key is used for panning
  • boost: {enabled: true} : this is used to tell the chart to use the boost module
  • tooltip: the tooltip is generated by default, but by using formatter(), we can specify exactly how it will look. Here, we have access (by this keyword) for each series attribute.
  • series: this is where we put the processed array of highcharts objects
  • xAxis: it’s used for informing chart, what is the type of series, specifying title, label format, and lots of other things.

The list of values that can be set for any of those attributes can be found here.

And, honestly, this is all. By moving processing logic to the store, we won’t cause any unnecessary computations inside of the component, which will improve speed immensely. In ChartFiltrations.vue, we can add some buttons to add additional filtrations to the chart. For example, we can add buttons to specify if we want to see only one type of attribute (remember that we need to still do the filtrations inside the store). Additionally, as in this example, we have both current and voltage. As you should know, they have different units, so to make our chart more lucid, we can use multiple y axises. It can be done simply by adding a yAxis object:

  yAxis: [
    {
      title: { text: 'Current [A]' },
      gridLineWidth: 0.5,
      showEmpty: false
    },
    {
      title: { text: 'Voltage [V]' },
      gridLineWidth: 0.5,
      showEmpty: false
    }
  ]

to the chartOptions object, specifying to which y axis the dataset belongs while creating highcharts series objects:

const generateSeries = data => {
  return Object.keys(data).map(attribute => {
    return {
      type: "line",
      yAxis: attribute === "current" ? 0 : 1
    };
  });
};

Let’s see how it looks in action:

As you can see, we had two series of 100k points, and they are working smoothly. In our project, sometimes we have 1 mln points to show at once, and performance is still superb. So, we can say with certainty that Highcharts fulfills its role, for sure.

In this article, I have hopefully shown you that lots of data does not come with a need to make performance cuts. This implementation is only one of numerous approaches to this particular topic. If you have any comments or questions, I will be happy to answer them through the comments.

You can find a working example here.