In this blog, we are going to learn how to perform CRUD (Create, Read, Update and Delete) operations with the help of Rest API using Node.js, MongoDB as our database, and Expess.

REST

In simple terms, REST stands for Representational State Transfer. It is an architectural style design for distributed hypermedia, or an Application Programming Interface (API). In REST, we use various standard HTTP methods like GET , POST , PUT and DELETE to perform any CRUD operation on resource.

Resource

In REST , everything is Resource . A resource can be an image, document, a temporary service, a collection of other resource, and any other object. Each resource has resource identifier to identify it.

HTTP Methods for CRUD

As per REST guidelines, we should use only HTTP methods to perform CRUD operation on any resource. In this blog, we are going to use 4 HTTP methods like GET , POST , PUT and DELETE to make our REST API.

Let’s have a brief introduction of each http method here.

HTTP GET

The HTTP GET is used to Read or Retrieve any resource. It returns the XML or JSON data with HTTP status code of 200. GET method is considered as safe, because we are just getting or reading the resource data, not doing any changes in the resource data.

HTTP POST

The HTTP POST is used to Create a new resource. On successful creation of resource, it will return HTTP status code of 201, a Location header with a link to the newly created resource.

HTTP PUT

The HTTP PUT is used to Update any existing resource. On successful, it will return HTTP status code of 200.

HTTP DELETE

The HTTP DELETE , as the name suggests, is used to Delete any existing resource. On successful, it will return HTTP status code of 200.

HTTP Methods CRUD Status Code GET Read 200 (OK), 404 (Not Found) POST Create 201 (OK), 404 (Not Found), PUT Update 200 (OK), 204 (No Content), 404 (Not Found) DELETE Delete 200 (OK), 404 (Not Found)

Let’s move forward into the details of other pieces of creating our REST API.

Express.js

We are going to use Express.js or simply Express. It is a web application framework for Node.js. It has been released as free and open source software. You can create web application and APIs using Express. It has support for routing, middleware, view system etc.

Mongoose

Mongoose is Object Document Mapping or ODM tool for Node.js and MongoDB. Mongoose provide a straight-forward, schema based solution to model to your application data. It includes built-in type casting, validation, query building, business logic hooks and many more.

Prerequisites

You must have Node.js and MongoDB installed on your machine. Click the below links, if you don’t have any one of them.

Install Node.js

Install MongoDB

For MongoDB, I am using mLab free account for online MongoDB database. You can try this one as well, instead of installing on your local machine.

Database-as-a-Service for MongoDB

Install Postman – Google Chrome for testing purpose.

After setting up prerequisites, let move forward to build our application.

Application Introduction

In our application, we are going to create a product based application. We will use REST APIs to create, update, get and delete the product. Let’s go to create our application.

1. Create package.json

Let’s create a folder, and start with creating package.json file first. Use this command in your terminal window.

npm init

package.json

If you notice line 5, we have defined server.js as our main entry point.

2. Install Packages

Let’s install all the express , mongoose and body-parser package dependencies in our app.

npm install express body-parser mongoose –save

Once these packages installed successfully, our package.json file will be updated automatically. Our latest file will be like this.

package.json

Notice dependencies section of our file, all these packages are mentioned there.

3. Creating Our Server

Let’s create a server.js file in the root directory of the application.

server.js

Let’s briefly review our above code. First of all, we imported the required dependencies in our server.js file.

body-parser

It is Node.js body parser middleware. It parse the incoming request bodies in a middleware before your handlers, available under the req.body property.

Learn more about bodyParser.urlencoded([options])

Learn more about bodyParser.json([options])

Then, we define a default route using GET Http method. By default, it will return our message on default url.

Finally, we are going to listen all incoming requests on port 3000.

4. Run the server

Once everything is all set, let’s wake up our server by running this command in our terminal window.

node server.js Server is listening on port 3000

5. Create Configuration file

Let’s create a config file in our app, where we can define various constants like dbconnection or port number instead of hard-coded it everywhere. So, create a config.js file in your app folder.

config.js

So, here I mentioned two constants in config.js file.

url: Our MongodB connection url.

serverport: Our listening server port.

6. Connecting to Database

Let’s connect with our MongoDb database. Add these lines of codes in server.js file after the app.use(bodyParser.json());

Also, we are going to replace our hard-coded server port with our config constant in server.js file

Here, you can see, we are now using config.serverport in app.listen().

Now, run again the server using this command.

node server.js

Server is listening on port 3000

Successfully connected to the database

7. Creating Product Model

Let’s create a product model in our app folder in order to save the data in our db. Create a product.model.js file in your app.

product.model.js

Here, we have defined our ProductSchema with following properties. Along with this, we also set timestamps property to true . This property will add two fields automatically to schema. These fields are : createdAt and updatedAt in your schema.

8. Creating our Controller’s functions

We are going to write all functions related to create, retrieve, update and delete products in our controller file. Let’s create a controller file named product.controller.js in your app folder.

product.controller.js

9. Defining Product API’s Routes

Next step is to create our api routes. Create a product.routes.js file in your app folder.

product.routes.js

Note: import this route file in our server.js file after these lines. See line 4 in the below code.

10. Enable the CORS

If you try to access your api routes through your client-side app, you might face Access-Control-Allow-Origin error messages. So, in order to avoid these message, we are also enabling CORS in our server.js file.

server.js

So, this will be our final server.js file.

server.js

This will be our project structure.

Testing our REST APIs

Now, it’s time to test our all REST APIs for CRUD Operation.

Create Product

I have added few products in the database. See the below screen shot.

Get All Products

Get Single Product

Update Product

Before Update

After Update

Delete Product

Download

You can download all the project files from GitHub.

Summary

In this blog, we learned about how to create a Node.js RESTful API app. We learned about how to perform CRUD operation on MongoDB database. Also, We learned about how to call our APIs endpoint in POSTMAN, and get the results.

Further Reading

Install Node.js and NPM on hosting server

Update Angular 6 to Angular 7 version

Creating your first app in Angular 7

Please visit How to Download & Install MongoDB on Windows to read more about MongoDB.

Like this: Like Loading...