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.
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.
Alexander
8 Jan 2019The best article on CRUD I’ve ever red
Adesh
8 Jan 2019Thank you
Alexander
8 Jan 2019The best article on CRUD I’ve ever read
Rakesh S
9 Jan 2019Just what I was looking for really great article! I am really new to UI/frontend/REST but is it a thing in web development world to name things “res”, “req”, “err”. The code that I am looking at work has things named like that.
Thanks again.
Adesh
9 Jan 2019Thank you Rakesh
sandy
11 Jan 2019Hey guys,
MongooseError: The
uriparameter toopenUri()must be a string, got “undefined”. Make sure the first parameter tomongoose.connect()ormongoose.createConnection()is a string.Happend after created config.js when running node server.js.
I got this error . Google results this –> https://stackoverflow.com/questions/51770772/mongoose-connect-first-argument-should-be-string-received-undefined
Cofused and stuck. Any help would be appreciable. Have a nice day
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Tharinda Divakara
13 Jan 2019The article explains everything in details.
Adesh
13 Jan 2019Thanks
Ankit
27 Jan 2019Hello sir,
Could you explain what is happening on line 22 in final server.js file where we are requiring product.routes.js file.
I understood that we are requiring routes file, but why are we passing (app) as the parameter and how app is being used in product.routes.js file.
Thank you
Edward
28 Jan 2019Hi Adesh i really appreciate the efforts portrayed in this blog. Your article is comprehensive and very clear making it my go to reference whenever i’m stack and need help in creating Rest Apis. However,I could really appreciate your help in embedding mongoose schemas. I have basic understanding about the workings of mongoose but i can’t find my way through embedding documents. Thanks.
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Joel Meaders
17 Feb 2019Thanks a lot for this tutorial.
I’m not done yet but I wanted to share something I had an issue with and how it was solved as it might be worth mentioning. In part 6 (connecting to db) I was getting the error “MongoParseError: URI malformed, cannot be parsed”. I ended up figuring out it was because I had special characters in the password for my mongodb user. I fixed it by modifying config.js with the layout here https://stackoverflow.com/a/54626342 and then adapting mongoose.connect in server.js to use the auth portion.
Cihan
27 Mar 2019Great article
fernando
3 Apr 2019Adesh, Mongoose encapsulates bank functions for findOne, find, insert, update, updateOne, and remove? Is that the idea?
Anthony
14 Apr 2019Great and easy explanation, thank you for sharing
Nayanka
19 Apr 2019Hi sir please why do you used res.send in your controller file.And not res.json({}) ?