How to setup a powerful API with GraphQL, Koa and MongoDB

How to setup a powerful API with GraphQL, Koa and MongoDB

Building API’s is super fun! Especially when you can leverage modern technologies such as Koa, GraphQL and MongoDB.

Building API’s is super fun! Especially when you can leverage modern technologies such as Koa, GraphQL and MongoDB.

Koa is a Node framework, just like Express is a Node framework. We’ll replace Express with Koa since Koa uses async/await syntax over callbacks.

Koa Github repository

Express Github repository

Getting started

The prerequisites for building our API are the following;

  • Node installed
  • Text Editor; I pick Visual Studio Code
  • Terminal
  • Browser

If you have everything you need, please proceed - if not, please install them.

Open your terminal and create a node project, like so;

So far we created our project folder, initialized a fresh Node project. Now we have the NPM packages available which we can use to install Koa, Mongo, and GraphQL.

Let’s install koa with NPM.

npm i koa

Starting a new Koa server is very simple. All we need is a server.js file and with the contents;

const Koa = require('koa');

const app = new Koa();

app.listen(9000);

app.on('error', err => {
  log.error('server error', err)
});

Starting the project with Node

GraphQL

We need two packages to setup GraphQL with Koa. koa-mount and koa-graphql.

npm i koa-mount koa-graphql

GraphQL requires we pass our initial schema to the GraphQL server. Let’s create one.

We will place the graphQL schema at graphql/schema.js

const { buildSchema } = require('graphql');

const schema = buildSchema(`
  type Query {
    hello: String
  }
`);

module.exports = schema;

We pass our initial Query to the buildSchema function

Note: Notice how the argument for the buildSchema is a template literal. I encourage you take a look at this article if this is unfamiliar.

And now we can pass the initial schema to our graphql server.

app.use(mount('/graphql', graphqlHTTP({
  schema: schema,
  graphiql: true
})))

Don’t forget to import koa-mount, koa-graphql, and finally the schema.js.

const mount = require('koa-mount');
const graphqlHTTP = require('koa-graphql');
const schema = require('./graphql/schema');

If we head over to localhost:9000/graphql;

Voila! Initial setup is done. It’s not very useful yet. Ideally, we would like to query GraphQL to save data to our mongodb and read from there.

Setting up MongoDB

In order to read and write with GraphQL, we need a place to read from. This is where Mongo will come in handy. We’ll save and read our data from there.

To make things simpler, we’re gonna use a cloud instance for Mongo. Head over to mlab.com and create a user and a mongo database.

Creating mongoDB

Once you created the database–you’ll need a user for the database.

Creating the MongoDB user

Now you can use the mongoDB paired with Mongoose. The remote url for your database will be;

mongodb://:@ds213615.mlab.com:13615/koa-graphql

Installing mongose

npm i mongoose

Creating database.js file

We create a dedicated file for databse connection.

const mongoose = require('mongoose');

const initDB = () => {

  mongoose.connect(
    'mongodb://indrek:[email protected]:13615/koa-graphql',
    { useNewUrlParser: true }
  );

  mongoose.connection.once('open', () => {
    console.log('connected to database');
  });

}

module.exports = initDB;

Note: Make sure you use the username and credentials for your database.

This block of code will try to connect to the remote mongodb. We need to call it somewhere now.

Open server.js and require and call the method.

const initDB = require('./database');

initDB();

If we did everything correct, our console should tell us we connected succesfully.

Bravo!

Notice how annoying it is to constantly refresh the server. Let’s solve this with a package called pm2

PM2 is a production process manager for Node.js applications with a built-in load balancer. It allows you to keep applications alive forever, to reload them without downtime and to facilitate common system admin tasks.

npm install pm2 -g

Add a script called start to our package.json

"scripts": {
  "start": "pm2 start server.js"
},

Very lovely for pm2 to run in the background, which frees up our terminal. If you ever want to stop the process, just run pm2 kill. Now we don’t have to restart our server all the time, pm2 does it automatically.

Note: pm2 logs returns the console log statements to the terminal.

MongoDB models

If you ever worked Mongo, you’re aware that mongoDB let’s us creates Models for our data. This is a neat way for us to structure how our data will look like.

Create a folder models and inside a file gadgets.js

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

/*
  notice there is no ID. That's because Mongoose will assign
  an ID by default to all schemas
*/

const GadgetSchema = new Schema({
  name: String,
  release_date: Date,
  by_company: String,
  price: Number,
});

module.exports = mongoose.model('Gadget', GadgetSchema);

Note: There is no ID field in our schema. That’s because Mongoose will assign

an ID by default to all schemas

Great. Let’s also add a collection and some dummy data. The collection name has to map our gadget name in plural. gadgets in this case.

After creating the collection, insert the document in JSON format like so;

That’s all for Mongo. Let’s fetch the data with GraphQL.

GraphQL Queries

GraphQL requires us to create types as well. Think of it like instructions for computers.

graphql/gadgetType.js

const graphql = require('graphql');

const { GraphQLObjectType, GraphQLString } = graphql;

const GadgetType = new GraphQLObjectType({
  name: 'Gadget',
  fields: () => ({

  })
});

module.exports = GadgetType;

Notice we created a graphql type. Inside the fields we can specify the properties of the given type.

const graphql = require('graphql');

const { GraphQLObjectType, GraphQLObjectType } = graphql;

const GadgetType = new GraphQLObjectType({
  name: 'Gadget',
  fields: () => ({
    id: { type: GraphQLString },
    name: { type: GraphQLString },
    release_date: { type: GraphQLString },
    by_company: { type: GraphQLString },
    price: { type: GraphQLString }
  })
});

module.exports = GadgetType;

Notice the GraphQLObjectType and GraphQLObjectType types we deconstruct from graphQL. These are the primitive types for graphQL.

Creating the graphQL types also grants type-hinting which we’ll use when creating our queries.

Last thing we need to do is refactor our schema.js. We want to query a gadget by id.

import the Gadget model,gadgetGraphQLType graphql type and GraphQLSchema, GraphQLObjectType, GraphQLString from graphQL to schema.js.

const { GraphQLSchema, GraphQLObjectType, GraphQLString} = require('graphql');
const gadgetGraphQLType =  require('./gadgetType');
const Gadget = require('../models/gadget');

Next we need a root query. Every graphql query starts with curly brackets {} – this the root query.

const RootQuery = new GraphQLObjectType({
  name: 'RootQueryType',
  fields: {

  }
})

Voila! Inside the fields we can specify the gadget query.

const RootQuery = new GraphQLObjectType({
  name: 'RootQueryType',
  fields: {
    gadget: {
      type: gadgetGraphQLType,
      args: { id: { type: GraphQLString }},
      resolve(parent, args) {
        return Gadget.findById(args.id)
      }
    }
  }
})

Notice the three properties inside the gadget query.

  • Node installed
  • Text Editor; I pick Visual Studio Code
  • Terminal
  • Browser

And finally export it.

module.exports = new GraphQLSchema({
  query: RootQuery
});

The file schema.js file should look like this;

const { GraphQLSchema, GraphQLObjectType, GraphQLString} = require('graphql');
const gadgetGraphQLType =  require('./gadgetType');
const Gadget = require('../models/gadget');

const RootQuery = new GraphQLObjectType({
  name: 'RootQueryType',
  fields: {
    gadget: {
      type: gadgetGraphQLType,
      args: { id: { type: GraphQLString }},
      resolve(parent, args) {
        return Gadget.findById(args.id)
      }
    }
  }
})

module.exports = new GraphQLSchema({
  query: RootQuery
});

Now head over to http://localhost:9000/graphql and make the query.

{
	gadget(id: "5c4e188efb6fc05326ad9264") {
		name
    price
    by_company
    release_date
    id
  }
}

This it what we should end up with!

Thanks for reading! ❤ The source code can be found here.

How to Use Express.js, Node.js and MongoDB.js

How to Use Express.js, Node.js and MongoDB.js

In this post, I will show you how to use Express.js, Node.js and MongoDB.js. We will be creating a very simple Node application, that will allow users to input data that they want to store in a MongoDB database. It will also show all items that have been entered into the database.

In this post, I will show you how to use Express.js, Node.js and MongoDB.js. We will be creating a very simple Node application, that will allow users to input data that they want to store in a MongoDB database. It will also show all items that have been entered into the database.

Creating a Node Application

To get started I would recommend creating a new database that will contain our application. For this demo I am creating a directory called node-demo. After creating the directory you will need to change into that directory.

mkdir node-demo
cd node-demo

Once we are in the directory we will need to create an application and we can do this by running the command
npm init

This will ask you a series of questions. Here are the answers I gave to the prompts.

The first step is to create a file that will contain our code for our Node.js server.

touch app.js

In our app.js we are going to add the following code to build a very simple Node.js Application.

var express = require("express");
var app = express();
var port = 3000;
 
app.get("/", (req, res) => {
  res.send("Hello World");
});
 
app.listen(port, () => {
  console.log("Server listening on port " + port);
});

What the code does is require the express.js application. It then creates app by calling express. We define our port to be 3000.

The app.use line will listen to requests from the browser and will return the text “Hello World” back to the browser.

The last line actually starts the server and tells it to listen on port 3000.

Installing Express

Our app.js required the Express.js module. We need to install express in order for this to work properly. Go to your terminal and enter this command.

npm install express --save

This command will install the express module into our package.json. The module is installed as a dependency in our package.json as shown below.

To test our application you can go to the terminal and enter the command

node app.js

Open up a browser and navigate to the url http://localhost:3000

You will see the following in your browser

Creating Website to Save Data to MongoDB Database

Instead of showing the text “Hello World” when people view your application, what we want to do is to show a place for user to save data to the database.

We are going to allow users to enter a first name and a last name that we will be saving in the database.

To do this we will need to create a basic HTML file. In your terminal enter the following command to create an index.html file.

touch index.html

In our index.html file we will be creating an input filed where users can input data that they want to have stored in the database. We will also need a button for users to click on that will add the data to the database.

Here is what our index.html file looks like.

<!DOCTYPE html>
<html>
  <head>
    <title>Intro to Node and MongoDB<title>
  <head>

  <body>
    <h1>Into to Node and MongoDB<&#47;h1>
    <form method="post" action="/addname">
      <label>Enter Your Name<&#47;label><br>
      <input type="text" name="firstName" placeholder="Enter first name..." required>
      <input type="text" name="lastName" placeholder="Enter last name..." required>
      <input type="submit" value="Add Name">
    </form>
  <body>
<html>

If you are familiar with HTML, you will not find anything unusual in our code for our index.html file. We are creating a form where users can input their first name and last name and then click an “Add Name” button.

The form will do a post call to the /addname endpoint. We will be talking about endpoints and post later in this tutorial.

Displaying our Website to Users

We were previously displaying the text “Hello World” to users when they visited our website. Now we want to display our html file that we created. To do this we will need to change the app.use line our our app.js file.

We will be using the sendFile command to show the index.html file. We will need to tell the server exactly where to find the index.html file. We can do that by using a node global call __dirname. The __dirname will provide the current directly where the command was run. We will then append the path to our index.html file.

The app.use lines will need to be changed to
app.use("/", (req, res) => {   res.sendFile(__dirname + "/index.html"); });

Once you have saved your app.js file, we can test it by going to terminal and running node app.js

Open your browser and navigate to “http://localhost:3000”. You will see the following

Connecting to the Database

Now we need to add our database to the application. We will be connecting to a MongoDB database. I am assuming that you already have MongoDB installed and running on your computer.

To connect to the MongoDB database we are going to use a module called Mongoose. We will need to install mongoose module just like we did with express. Go to your terminal and enter the following command.
npm install mongoose --save

This will install the mongoose model and add it as a dependency in our package.json.

Connecting to the Database

Now that we have the mongoose module installed, we need to connect to the database in our app.js file. MongoDB, by default, runs on port 27017. You connect to the database by telling it the location of the database and the name of the database.

In our app.js file after the line for the port and before the app.use line, enter the following two lines to get access to mongoose and to connect to the database. For the database, I am going to use “node-demo”.

var mongoose = require("mongoose"); mongoose.Promise = global.Promise; mongoose.connect("mongodb://localhost:27017/node-demo");

Creating a Database Schema

Once the user enters data in the input field and clicks the add button, we want the contents of the input field to be stored in the database. In order to know the format of the data in the database, we need to have a Schema.

For this tutorial, we will need a very simple Schema that has only two fields. I am going to call the field firstName and lastName. The data stored in both fields will be a String.

After connecting to the database in our app.js we need to define our Schema. Here are the lines you need to add to the app.js.
var nameSchema = new mongoose.Schema({   firstName: String,   lastNameName: String });

Once we have built our Schema, we need to create a model from it. I am going to call my model “DataInput”. Here is the line you will add next to create our mode.
var User = mongoose.model("User", nameSchema);

Creating RESTful API

Now that we have a connection to our database, we need to create the mechanism by which data will be added to the database. This is done through our REST API. We will need to create an endpoint that will be used to send data to our server. Once the server receives this data then it will store the data in the database.

An endpoint is a route that our server will be listening to to get data from the browser. We already have one route that we have created already in the application and that is the route that is listening at the endpoint “/” which is the homepage of our application.

HTTP Verbs in a REST API

The communication between the client(the browser) and the server is done through an HTTP verb. The most common HTTP verbs are
GET, PUT, POST, and DELETE.

The following table explains what each HTTP verb does.

HTTP Verb Operation
GET Read
POST Create
PUT Update
DELETE Delete

As you can see from these verbs, they form the basis of CRUD operations that I talked about previously.

Building a CRUD endpoint

If you remember, the form in our index.html file used a post method to call this endpoint. We will now create this endpoint.

In our previous endpoint we used a “GET” http verb to display the index.html file. We are going to do something very similar but instead of using “GET”, we are going to use “POST”. To get started this is what the framework of our endpoint will look like.

app.post("/addname", (req, res) => {
 
});
Express Middleware

To fill out the contents of our endpoint, we want to store the firstName and lastName entered by the user into the database. The values for firstName and lastName are in the body of the request that we send to the server. We want to capture that data, convert it to JSON and store it into the database.

Express.js version 4 removed all middleware. To parse the data in the body we will need to add middleware into our application to provide this functionality. We will be using the body-parser module. We need to install it, so in your terminal window enter the following command.

npm install body-parser --save

Once it is installed, we will need to require this module and configure it. The configuration will allow us to pass the data for firstName and lastName in the body to the server. It can also convert that data into JSON format. This will be handy because we can take this formatted data and save it directly into our database.

To add the body-parser middleware to our application and configure it, we can add the following lines directly after the line that sets our port.

var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
Saving data to database

Mongoose provides a save function that will take a JSON object and store it in the database. Our body-parser middleware, will convert the user’s input into the JSON format for us.

To save the data into the database, we need to create a new instance of our model that we created early. We will pass into this instance the user’s input. Once we have it then we just need to enter the command “save”.

Mongoose will return a promise on a save to the database. A promise is what is returned when the save to the database completes. This save will either finish successfully or it will fail. A promise provides two methods that will handle both of these scenarios.

If this save to the database was successful it will return to the .then segment of the promise. In this case we want to send text back the user to let them know the data was saved to the database.

If it fails it will return to the .catch segment of the promise. In this case, we want to send text back to the user telling them the data was not saved to the database. It is best practice to also change the statusCode that is returned from the default 200 to a 400. A 400 statusCode signifies that the operation failed.

Now putting all of this together here is what our final endpoint will look like.

app.post("/addname", (req, res) => {
  var myData = new User(req.body);
  myData.save()
    .then(item => {
      res.send("item saved to database");
    })
    .catch(err => {
      res.status(400).send("unable to save to database");
    });
});
Testing our code

Save your code. Go to your terminal and enter the command node app.js to start our server. Open up your browser and navigate to the URL “http://localhost:3000”. You will see our index.html file displayed to you.

Make sure you have mongo running.

Enter your first name and last name in the input fields and then click the “Add Name” button. You should get back text that says the name has been saved to the database like below.

Access to Code

The final version of the code is available in my Github repo. To access the code click here. Thank you for reading !

How to Build a RESTful API in Node.js, Express.js & MongoDB (Mongoose)

How to Build a RESTful API in Node.js, Express.js & MongoDB (Mongoose)

How to Build a RESTful API in Node.js, Express.js and MongoDB (Mongoose). Learn to create your first RESTful API in NodeJS, ExpressJS, and MongoDB (mongoose). We cover the MVC pattern, CRUD, Routes, Error Handling, ES6, Promises, GET, POST, DELETE in under 50 minutes. Learn to build a REST API to create,modify and delete users in a database. Build a simple API using ExpressJs and MongoDb with CRUD functions for Contacts.

How to Build a RESTful API in Node.js, Express.js & MongoDB (Mongoose)

Learn to create your first RESTful API in NodeJS, ExpressJS, and MongoDB (mongoose).

We cover the MVC pattern, CRUD, Routes, Error Handling, ES6, Promises, GET, POST, DELETE in under 50 minutes. Learn to build a REST API to create,modify and delete users in a database. Build a simple API using ExpressJs and MongoDb with CRUD functions for Contacts.

Build a REST API using Node.js, Express.js, Mongoose.js and MongoDB

Build a REST API using Node.js, Express.js, Mongoose.js and MongoDB

Node.js, Express.js, Mongoose.js, and MongoDB is a great combination for building easy and fast REST API. You will see how fast that combination than other existing frameworks because of Node.js is a packaged compilation of Google’s V8 JavaScript engine and it works on non-blocking and event-driven I/O. Express.js is a Javascript web server that has a complete function of web development including REST API.

Node.js, Express.js, Mongoose.js, and MongoDB is a great combination for building easy and fast REST API. You will see how fast that combination than other existing frameworks because of Node.js is a packaged compilation of Google’s V8 JavaScript engine and it works on non-blocking and event-driven I/O. Express.js is a Javascript web server that has a complete function of web development including REST API.

This tutorial divided into several steps:

Step #1. Create Express.js Application and Install Required Modules
Step #2. Add Mongoose.js Module as ORM for MongoDB
Step #3. Create Product Mongoose Model
Step #4. Create Routes for the REST API endpoint
Step #5. Test REST API Endpoints

Source codes here:
https://github.com/didinj/NodeRestApi...