Build a CRUD Rest Api example using Node.js, Express & MongoDb

 Express is one of the most popular web frameworks for Node.js that supports routing, middleware, view system… Mongoose is a promise-based Node.js ODM for MongoDB that provides a straight-forward, schema-based solution to model our application data along with built-in type casting, validation, query building, business logic hooks… In this tutorial, I will show you step by step to build Node.js Restful API for CRUD operations using Express, Mongoose with MongoDB database.

You should install MongoDB in your machine first. The installation instructions can be found at Official MongoDB installation manual.

Node.js MongoDB Rest CRUD API overview

We will build Rest Apis that can create, retrieve, update, delete and find Tutorials by title.

First, we start with an Express web server. Next, we add configuration for MongoDB database, create Tutorial model with Mongoose, write the controller. Then we define routes for handling all CRUD operations (including custom finder).

The following table shows overview of the Rest APIs that will be exported:

Methods	Urls	Actions
GET	api/tutorials	get all Tutorials
GET	api/tutorials/:id	get Tutorial by id
POST	api/tutorials	add new Tutorial
PUT	api/tutorials/:id	update Tutorial by id
DELETE	api/tutorials/:id	remove Tutorial by id
DELETE	api/tutorials	remove all Tutorials
GET	api/tutorials/published	find all published Tutorials
GET	api/tutorials?title=[kw]	find all Tutorials which title contains 'kw'

Finally, we’re gonna test the Rest Apis using Postman.

This is our project structure:

Create Node.js App

First, we create a folder:

$ mkdir nodejs-express-mongodb
$ cd nodejs-express-mongodb

Next, we initialize the Node.js App with a package.json file:

npm init

name: (nodejs-express-mongodb) 
version: (1.0.0) 
description: Node.js Restful CRUD API with Node.js, Express and MongoDB
entry point: (index.js) server.js
test command: 
git repository: 
keywords: nodejs, express, mongodb, rest, api
author: bezkoder
license: (ISC)

Is this ok? (yes) yes

We need to install necessary modules: express, mongoose, body-parser and cors.
Run the command:

npm install express mongoose body-parser cors --save

The package.json file should look like this:

{
  "name": "node-express-mongodb",
  "version": "1.0.0",
  "description": "Node.js Restful CRUD API with Node.js, Express and MongoDB",
  "main": "server.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [
    "nodejs",
    "express",
    "rest",
    "api",
    "mongodb"
  ],
  "author": "bezkoder",
  "license": "ISC",
  "dependencies": {
    "body-parser": "^1.19.0",
    "cors": "^2.8.5",
    "express": "^4.17.1",
    "mongoose": "^5.8.10"
  }
}

Setup Express web server

In the root folder, let’s create a new server.js file:

const express = require("express");
const bodyParser = require("body-parser");
const cors = require("cors");

const app = express();

var corsOptions = {
  origin: "http://localhost:8081"
};

app.use(cors(corsOptions));

// parse requests of content-type - application/json
app.use(bodyParser.json());

// parse requests of content-type - application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ extended: true }));

// simple route
app.get("/", (req, res) => {
  res.json({ message: "Welcome to bezkoder application." });
});

// set port, listen for requests
const PORT = process.env.PORT || 8080;
app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}.`);
});

What we do are:
– import express, body-parser and cors modules:

• Express is for building the Rest apis
• body-parser helps to parse the request and create the req.body object
• cors provides Express middleware to enable CORS with various options.

– create an Express app, then add body-parser and cors middlewares using app.use() method. Notice that we set origin: http://localhost:8081.
– define a GET route which is simple for test.
– listen on port 8080 for incoming requests.

Now let’s run the app with command: node server.js.
Open your browser with url http://localhost:8080/, you will see:

Yeah, the first step is done. We’re gonna work with Mongoose in the next section.

Configure MongoDB database & Mongoose

In the app folder, we create a separate config folder for configuration with db.config.js file like this:

module.exports = {
  url: "mongodb://localhost:27017/bezkoder_db"
};

Define Mongoose

We’re gonna define Mongoose model (tutorial.model.js) also in app/models folder in the next step.

Now create app/models/index.js with the following code:

const dbConfig = require("../config/db.config.js");

const mongoose = require("mongoose");
mongoose.Promise = global.Promise;

const db = {};
db.mongoose = mongoose;
db.url = dbConfig.url;
db.tutorials = require("./tutorial.model.js")(mongoose);

module.exports = db;

Don’t forget to call connect() method in server.js:

...
const app = express();
app.use(...);

const db = require("./app/models");
db.mongoose
  .connect(db.url, {
    useNewUrlParser: true,
    useUnifiedTopology: true
  })
  .then(() => {
    console.log("Connected to the database!");
  })
  .catch(err => {
    console.log("Cannot connect to the database!", err);
    process.exit();
  });

Define the Mongoose Model

In models folder, create tutorial.model.js file like this:

module.exports = mongoose => {
  const Tutorial = mongoose.model(
    "tutorial",
    mongoose.Schema(
      {
        title: String,
        description: String,
        published: Boolean
      },
      { timestamps: true }
    )
  );

  return Tutorial;
};

This Mongoose Model represents tutorials collection in MongoDB database. These fields will be generated automatically for each Tutorial document: _id, title, description, published, createdAt, updatedAt, __v.

{
  "_id": "5e363b135036a835ac1a7da8",
  "title": "Js Tut#",
  "description": "Description for Tut#",
  "published": true,
  "createdAt": "2020-02-02T02:59:31.198Z",
  "updatedAt": "2020-02-02T02:59:31.198Z",
  "__v": 0
}

If you use this app with a front-end that needs id field instead of _id, you have to override toJSON method that map default object to a custom object. So the Mongoose model could be modified as following code:

module.exports = mongoose => {
  var schema = mongoose.Schema(
    {
      title: String,
      description: String,
      published: Boolean
    },
    { timestamps: true }
  );

  schema.method("toJSON", function() {
    const { __v, _id, ...object } = this.toObject();
    object.id = _id;
    return object;
  });

  const Tutorial = mongoose.model("tutorial", schema);
  return Tutorial;
};

And the result will look like this-

{
  "title": "Js Tut#",
  "description": "Description for Tut#",
  "published": true,
  "createdAt": "2020-02-02T02:59:31.198Z",
  "updatedAt": "2020-02-02T02:59:31.198Z",
  "id": "5e363b135036a835ac1a7da8"
}

After finishing the steps above, we don’t need to write CRUD functions, Mongoose Model supports all of them:

• create a new Tutorial: object.save()
• find a Tutorial by id: findById(id)
• retrieve all Tutorials: find()
• update a Tutorial by id: findByIdAndUpdate(id, data)
• remove a Tutorial: findByIdAndRemove(id)
• remove all Tutorials: deleteMany()
• find all Tutorials by title: find({ title: { $regex: new RegExp(title), $options: “i” } })

These functions will be used in our Controller.

Create the Controller

Inside app/controllers folder, let’s create tutorial.controller.js with these CRUD functions:

• create
• findAll
• findOne
• update
• delete
• deleteAll
• findAllPublished

const db = require("../models");
const Tutorial = db.tutorials;

// Create and Save a new Tutorial
exports.create = (req, res) => {
  
};

// Retrieve all Tutorials from the database.
exports.findAll = (req, res) => {
  
};

// Find a single Tutorial with an id
exports.findOne = (req, res) => {
  
};

// Update a Tutorial by the id in the request
exports.update = (req, res) => {
  
};

// Delete a Tutorial with the specified id in the request
exports.delete = (req, res) => {
  
};

// Delete all Tutorials from the database.
exports.deleteAll = (req, res) => {
  
};

// Find all published Tutorials
exports.findAllPublished = (req, res) => {
  
};

Let’s implement these functions.

Create a new object

Create and Save a new Tutorial:

exports.create = (req, res) => {
  // Validate request
  if (!req.body.title) {
    res.status(400).send({ message: "Content can not be empty!" });
    return;
  }

  // Create a Tutorial
  const tutorial = new Tutorial({
    title: req.body.title,
    description: req.body.description,
    published: req.body.published ? req.body.published : false
  });

  // Save Tutorial in the database
  tutorial
    .save(tutorial)
    .then(data => {
      res.send(data);
    })
    .catch(err => {
      res.status(500).send({
        message:
          err.message || "Some error occurred while creating the Tutorial."
      });
    });
};

Retrieve objects (with condition)

Retrieve all Tutorials/ find by title from the database:

exports.findAll = (req, res) => {
  const title = req.query.title;
  var condition = title ? { title: { $regex: new RegExp(title), $options: "i" } } : {};

  Tutorial.find(condition)
    .then(data => {
      res.send(data);
    })
    .catch(err => {
      res.status(500).send({
        message:
          err.message || "Some error occurred while retrieving tutorials."
      });
    });
};

We use req.query.title to get query string from the Request and consider it as condition for findAll() method.

Retrieve a single object

Find a single Tutorial with an id:

exports.findOne = (req, res) => {
  const id = req.params.id;

  Tutorial.findById(id)
    .then(data => {
      if (!data)
        res.status(404).send({ message: "Not found Tutorial with id " + id });
      else res.send(data);
    })
    .catch(err => {
      res
        .status(500)
        .send({ message: "Error retrieving Tutorial with id=" + id });
    });
};

Update an object

Update a Tutorial identified by the id in the request:

exports.update = (req, res) => {
  if (!req.body) {
    return res.status(400).send({
      message: "Data to update can not be empty!"
    });
  }

  const id = req.params.id;

  Tutorial.findByIdAndUpdate(id, req.body, { useFindAndModify: false })
    .then(data => {
      if (!data) {
        res.status(404).send({
          message: `Cannot update Tutorial with id=${id}. Maybe Tutorial was not found!`
        });
      } else res.send({ message: "Tutorial was updated successfully." });
    })
    .catch(err => {
      res.status(500).send({
        message: "Error updating Tutorial with id=" + id
      });
    });
};

Delete an object

Delete a Tutorial with the specified id:

exports.delete = (req, res) => {
  const id = req.params.id;

  Tutorial.findByIdAndRemove(id)
    .then(data => {
      if (!data) {
        res.status(404).send({
          message: `Cannot delete Tutorial with id=${id}. Maybe Tutorial was not found!`
        });
      } else {
        res.send({
          message: "Tutorial was deleted successfully!"
        });
      }
    })
    .catch(err => {
      res.status(500).send({
        message: "Could not delete Tutorial with id=" + id
      });
    });
};

Delete all objects

Delete all Tutorials from the database:

exports.deleteAll = (req, res) => {
  Tutorial.deleteMany({})
    .then(data => {
      res.send({
        message: `${data.deletedCount} Tutorials were deleted successfully!`
      });
    })
    .catch(err => {
      res.status(500).send({
        message:
          err.message || "Some error occurred while removing all tutorials."
      });
    });
};

Find all objects by condition

Find all Tutorials with published = true:

exports.findAllPublished = (req, res) => {
  Tutorial.find({ published: true })
    .then(data => {
      res.send(data);
    })
    .catch(err => {
      res.status(500).send({
        message:
          err.message || "Some error occurred while retrieving tutorials."
      });
    });
};

This controller can be modified a little to return pagination response:

{
    "totalItems": 8,
    "tutorials": [...],
    "totalPages": 3,
    "currentPage": 1
}

You can find more details at:
Server side Pagination in Node.j with MongoDB & Mongoose

Define Routes

When a client sends request for an endpoint using HTTP request (GET, POST, PUT, DELETE), we need to determine how the server will reponse by setting up the routes.

These are our routes:

• /api/tutorials: GET, POST, DELETE
• /api/tutorials/:id: GET, PUT, DELETE
• /api/tutorials/published: GET

Create a turorial.routes.js inside app/routes folder with content like this:

module.exports = app => {
  const tutorials = require("../controllers/tutorial.controller.js");

  var router = require("express").Router();

  // Create a new Tutorial
  router.post("/", tutorials.create);

  // Retrieve all Tutorials
  router.get("/", tutorials.findAll);

  // Retrieve all published Tutorials
  router.get("/published", tutorials.findAllPublished);

  // Retrieve a single Tutorial with id
  router.get("/:id", tutorials.findOne);

  // Update a Tutorial with id
  router.put("/:id", tutorials.update);

  // Delete a Tutorial with id
  router.delete("/:id", tutorials.delete);

  // Create a new Tutorial
  router.delete("/", tutorials.deleteAll);

  app.use('/api/tutorials', router);
};

You can see that we use a controller from /controllers/tutorial.controller.js.

We also need to include routes in server.js (right before app.listen()):

...

require("./app/routes/turorial.routes")(app);

// set port, listen for requests
const PORT = ...;
app.listen(...);

Test the APIs

Run our Node.js application with command: node server.js.

Using Postman, we’re gonna test all the Apis above.

1. Create a new Tutorial using POST /tutorials Api




After creating some new Tutorials, you can check MongoDb collection:



2. Retrieve a single Tutorial by id using GET /tutorials/:id Api




3. Update a Tutorial using PUT /tutorials/:id Api




Check tutorials collection after some documents were updated:



4. Find all Tutorials which title contains ‘js’: GET /tutorials?title=js




5. Find all published Tutorials using GET /tutorials/published Api




6. Delete a Tutorial using DELETE /tutorials/:id Api




The Tutorial was removed from tutorials collection:



7. Delete all Tutorials using DELETE /tutorials Api

Conclusion

Today, we’ve learned how to create Node.js Rest Apis with an Express web server. We also know way to add configuration for MongoDB database & Mongoose, create a Mongoose Model, write a controller and define routes for handling all CRUD operations.

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