Beginning Node.js – REST API with a Mongodb backend – part 3

This is the sequel to this article. I’m building a REST API from the ground up with Node.js and Express.js 4. I’m adding functionality as I go. I’m starting with Node.js, then I’m adding Express and now I’m adding Mongoose. In the next articles I will be adding Passport.js for authentication and start building a frontend, either with Angular of Ember.

Things have changed slightly since my former series, see here. That’s because Express.js version 3 has evolved to version 4. The main difference between version 3 and 4 is that version 3 contains middleware (JSON parsers, session support and so on). In version 4 you need to add the middleware yourself. That means installing body-parser, session and so on with NPM.

In my former article we used a JSON string with data. Now let’s use a real data backend: MongoDb. Mongoose is an ORM for MongoDb for Node.js, so let’s add the module to the project:

npm install --save mongoose

We also need to install the body-parser, which parses JSON bodies for Express.

npm install --save body-parser

Next, copy all of this to your main.js file:

var express = require('express');
var app = express();
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
//mongoose uses Schema as a layer on a MongoDb document (which represents a model):
var Schema = mongoose.Schema;

app.use(bodyParser.urlencoded({
    extended: true
}));
app.use(bodyParser.json());

//connect to mongodb:
mongoose.connect('mongodb://localhost:27017/restaurant');

//create a Schema for our food:
var FoodSchema = new Schema({
    name: {
        type: String,
        index: {
            unique: true
        }
    },
    description: String,
    price: String
});


// Use the schema to register a model with MongoDb
mongoose.model('Food', FoodSchema);
var food = mongoose.model('Food');

//POST verb
app.post('/food', function (req, res) {
    food.create(req.body, function (err, food) {
        if (err) {
            res.send(401, err);
            return;
        }
        res.send(req.body);
    });
});

//GET verb
app.get('/food', function (req, res) {
    food.find(function (err, data) {
        if (err) {
            res.send(err);
        }
        res.json(data);
    });
});

//GET/id
app.get('/food/:id', function (req, res) {
    food.findOne({
        _id: req.params.id
    }, function (error, response) {
        if (error) {
            res.send(error);
        } else {
            res.send(response);
        }
    });
});

//GET by name
app.get('/foodname/:name', function (req, res) {
    food.findOne({
        name: req.params.name
    }, function (error, response) {
        if (error || !response) {
            res.send("not on the menu");
        } else {
            res.send(response);
        }
    });
});


app.set('port', process.env.PORT || 3000);
app.listen(app.get('port'));
console.log("the server is running on http://localhost:" + app.get('port'));

Now run it with the following command:

nodemon main.js

What happened?

Let’s dissect the code from the previous paragraph:

1.
We added and instantiated the prerequisites and connected to our MongodB instance

var bodyParser = require('body-parser');
var mongoose = require('mongoose');
//mongoose uses Schema as a layer on a MongoDb document (which represents a model):
var Schema = mongoose.Schema;

app.use(bodyParser.urlencoded({
    extended: true
}));
app.use(bodyParser.json());

//connect to mongodb:
mongoose.connect('mongodb://localhost:27017/restaurant');

2.
We create a Schema for our Food class:

//create a Schema for our food:
var FoodSchema = new Schema({
    name: {
        type: String,
        index: {
            unique: true
        }
    },
    description: String,
    price: String
});

3.
Then we used the schema to register a model with MongoDb
mongoose.model('Food', FoodSchema);
var food = mongoose.model('Food');

4.
And then we are ready to define our CRUD methods, e.g.

//POST verb
app.post('/food', function (req, res) {
    food.create(req.body, function (err, food) {
        if (err) {
            res.send(401, err);
            return;
        }
        res.send(req.body);
    });
});

//GET verb
app.get('/food', function (req, res) {
    food.find(function (err, data) {
        if (err) {
            res.send(err);
        }
        res.json(data);
    });
});

Using the API with Curl

You can add a menu item with the following command:

curl -H "Content-Type: application/json" -d '{ "name": "papadums", "description" : "Thin Bread", "price" : "2.00" }' http://localhost:3000/food

Issue a get:

curl http://localhost:3000/food

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