Simple REST API using Node,Express and MongoDB

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This is a beginners guide  to create a simple REST API which contains basic CRUD operations(Create,Read,Update,Delete) using Node.js,Express js framework and MongoDB.

Prerequisites

  •         Node js
  •         MongoDB
  •         WebStrome (IDE)
  •         RESTClient- to test the REST API

Creating the API

Open your WebStrome IDE and Go to File ->New -> Project >Empty Project Select  the location you want to create the project and hit Create button.

Folder Structure


Demo
|_______DBSchema
                  |_____DBConfig
|_______UserController
                  |_____Controller.js
                  |_____User.Route.js
|_______app.js
|_______Routes.js

     1st  we need to convert  this empty project into Node project(Initializing the application with package.json file.
     Open a terminal in the IDE or go to the Demo folder and open a terminal. And run npm init command ,enter all the dependencies (I kept all the dependencies as default) finally type yes.
     If you run the command right, package.json file should be automatically created in the Demo directory with the dependencies. 
   
     Then we need to add express, mongoose and body-parser modules .before that make sure that you’re connected to internet.Then run 
     npm intall express body-parser mongoose  --save 
command in the terminal.

     Create a app.js file in Demo directory


Demo
|_________node_modules
|_________package.json
|_________package-lock.json
|_________app.js


Inside the app.js file enter the following code.(app.js handles all the server requests.)

//Handles all the Server Request
const Express =require("express");
const BodyParser =require("body-parser");
const app = Express();
app.use(BodyParser.json());
app.listen(8088,'localhost',function (err) {
if(err){
     console.log(err);
     process.exit(-1);
}
  console.log("Server  listening port 8088")
})


Now run the app.js file using node app.js command.
create a directory as DBSchema to keep all the configuration files.create a javaScript file as DBConfig inside that directory and add the following code.


Demo
|_______node_modules
|_______package.json
|_______package-lock.json
|_______DBSchema
                        |_____DBConfig
        |_________app.js

create a directory named as UserController and create a javaScript file Controller.js inside that directory and add the following code.

Demo
|_______node_modules
|_______package.json
|_______package-lock.json
|_______DBSchema
                         |_____DBConfig
|_______UserController
                         |_____Controller.js
|_______app.js

var mongoose = require("../DBSchema/DBConfig");
var UserSchema = mongoose.model('User');
//create controller class and create functions in it
var Controller = function () {  }
module.exports = new Controller();
 

create another javaScript file User.Route.js inside the UserControlller directory and add the following code

var Express = require("express");
var router = Express.Router();
var Controller = require("./Controller");
module.exports = router;

Create a Routes.js file inside the Demo directory and add following code.(Router.js handles all the function paths)

Demo
|_______node_modules
|_______package.json
|_______package-lock.json
|_______DBSchema
                       |_____DBConfig
|_______UserController
                      |_____Controller.js
                      |_____User.Route.js

|_______app.js
|_______Routes.js

var Routes = Express.Router();
var UserRoute = require('./UserController/User.Route');
Routes.use('/user/', UserRoute);
module.exports = Routes;

Then modify app.js by adding these 2 lines of code
 
const Routes= require("./Routes");
app.use('/',Routes);

Perform CRUD operations
You need to download and install mongoDB if you haven’t installed into your machine before.

https://www.mongodb.com/download-center#community
If you have installed mongoDB in  C:\Program Files\MongoDB.
In the C: drive Create a folder called Data and inside that, create a folder called db
C:\data\db

Now go to C:\Program Files\MongoDB\Server\3.6\bin
Open a terminal and run the command mongod


Create User
 First Create a createUser function in the Controller.js file as follow.
this.CreateUser = function (data) {//to create asynchronous behavoir we use promisesreturn new Promise(function (resolve, reject) {
        var User = new UserSchema({
            _id:data._id,
            name: data.name,
            address: data.address,
            password: data.password
        });

        //save user details. save function in schema model

        User.save().then(function () {
        resolve({status: 200, message: "User inseted successfully!"});

        }).catch(function (err) {
            reject({status: 500, message: "Error: " + err});
        })
    });
};


 Then create a post request in User.Route.js file
router.post('/', function (req, res) {
    //.then use because og insertUser return a promise instance    Controller.CreateUser(req.body).then(function (data) {
        res.status(data.status).send({message: data.message});
    }).catch(function (err) {
        res.status(data.status).send({message: err.message});

    });
});


Run the server using the command node app.js

Open RESTClient from your firefox browser and set Requst headers as follow.And test POST request.if you get status code as 200.you have perform your get request successfully.





Get all users

Create a getAllUsers function in the Controller.js file as follow.

this.getAllUsers = function () {
    return new Promise(function (resolve, reject) {
        UserSchema.find().exec().then(function (data) {
            resolve({status: 200, Userdata: data});
        }).catch(function (err) {
            reject({status: 404, message: "No data"});
        })

    })

};

 Then create a GET request in User.Route.js file

router.get('/', function (req, res) {
    Controller.getAllUsers().then(function (data) {
        res.status(data.status).send({data: data.Userdata});
    }).catch(function (err) {
        res.status(data.status).send({message: err.message});
        console.log("error in get function")
    });
});

Run the server using node app.js








Get a particular User
Create a getUser function in the Controller.js file as follow.
this.getUser = function (id) {
    return new Promise(function (resolve, reject) {
        UserSchema.find({_id: id}).exec().then(function (data) {
            resolve({status: 200, userSearched: data});
        }).catch(function (err) {
            reject({status: 404, message: "No data"});
        })
    })
};




Then create a GET request in User.Route.js file
router.get('/:id', function (req, res) {
    Controller.getUser(req.params.id).then(function (data) {
        res.status(data.status).send({data: data.userSearched})
    }).catch(function (err) {
        res.status(data.status).send({message: err.message});

    })
});




Update User

Create a updateUser function in the Controller.js file as follow.

this.updateUser = function (id,data) {
    return new Promise(function (resolve,reject) {
        UserSchema.update({_id:id},data).then(function () {
            resolve({status:200,message:"User Updated!"})
        }).catch(function (err) {
            reject({status:500,message:"Error "+err});
        })

    })
};

Then create a PUT request in User.Route.js file

router.put('/:id',function (req,res){
    Controller.updateUser(req.params.id,req.body).then(function (data) {
        res.status(data.status).send({message:data.message});

    }).catch(function (err) {
        res.status(data.status).send({message: err.message});

    });

});





Delete User

Create a deleteUser function in the Controller.js file as follow.



this.deleteUser =function (id) {
    return new Promise(function (resolve,reject) {
        UserSchema.remove({_id:id}).exec().then(function (data) {
            resolve({status:200,Userdata:data});
        }).catch(function (err) {
            reject({status:404,message:"Cannot delete user"})
        })

    })

};
Then create a DELETE request in User.Route.js file
router.delete('/:id',function(req,res){
    Controller.deleteUser(req.params.id).then(function (data) {
        res.status(data.status).send(req.params.id+" deleted sucessfully");

    }).catch(function (err) {
        res.status(data.status).send({message: err.message});

    });

});

Comments

  1. PriyaJanuary 7, 2020 at 11:15 PM

    After seeing your article, I want to say that the presentation is very good and this is very useful for the readers .... thank you for sharing it.
    Node JS Online training
    Node JS training in Hyderabad

    ReplyDelete

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