###Creating a REST API using Node.js, Express, and MongoDB
####Installing Node.js
Go to http://nodejs.org, and click the Install button. Run the installer that you just downloaded. When the installer completes, a message indicates that Node was installed at /usr/local/bin/node and npm was installed at /usr/local/bin/npm. At this point node.js is ready to use. Let’s implement the webserver application from the nodejs.org home page. We will use it as a starting point for our project: a RESTful API to access data (retrieve, create, update, delete) in a wine cellar database.
Create a folder named nodecellar anywhere on your file system. In the wincellar folder, create a file named server.js. Code server.js as follows:
var http = require('http');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello World\n');
}).listen(3000, '127.0.0.1');
console.log('Server running at http://127.0.0.1:3000/');
We are now ready to start the server and test the application:
To start the server, open a shell, cd to your nodecellar directory, and start your server as follows: node server.js
To test the application, open a browser and access http://localhost:3000.
####Installing Express
Express is a lightweight node.js web application framework. It provides the basic HTTP infrastructure that makes it easy to create REST APIs.
To install Express in the nodecellar application:
In the nodecellar folder, create a file named package.json defined as follows:
{
"name": "wine-cellar",
"description": "Wine Cellar Application",
"version": "0.0.1",
"private": true,
"dependencies": {
"express": "3.x"
}
}
Open a shell, cd to the nodecellar directory, and execute the following command to install the express module. npm install
A node_modules folder is created in the nodecellar folder, and the Express module is installed in a subfolder of node_modules.
Now that Express is installed, we can stub a basic REST API for the nodecellar application:
Open server.js and replace its content as follows:
var express = require('express');
var app = express();
app.get('/wines', function(req, res) {
res.send([{name:'wine1'}, {name:'wine2'}]);
});
app.get('/wines/:id', function(req, res) {
res.send({id:req.params.id, name: "The Name", description: "description"});
});
app.listen(3000);
console.log('Listening on port 3000...');
view rawserver.js hosted with ❤ by GitHub
Stop (CTRL+C) and restart the server:
node server
To test the API, open a browser and access the following URLs: Get all the wines in the database: http://localhost:3000/wines Get wine with a specific id (for example: 1): http://localhost:3000/wines/1
####Using Node.js Modules
In a large application, things could easily get out of control if we keep adding code to a single JavaScript file (server.js). Let’s move the wine-related code in a wines module that we then declare as a dependency in server.js.
In the nodecellar folder, create a subfolder called routes. In the routes folder create a file named wines.js and defined as follows:
exports.findAll = function(req, res) {
res.send([{name:'wine1'}, {name:'wine2'}, {name:'wine3'}]);
};
exports.findById = function(req, res) {
res.send({id:req.params.id, name: "The Name", description: "description"});
};
Modify server.js as follows to delegate the routes implementation to the wines module:
var express = require('express'),
wines = require('./routes/wines');
var app = express();
app.get('/wines', wines.findAll);
app.get('/wines/:id', wines.findById);
app.listen(3000);
console.log('Listening on port 3000...');
Restart the server and test the APIs: Get all the wines in the database: http://localhost:3000/wines Get wine with a specific id (for example: 1): http://localhost:3000/wines/1 The next step is to replace the placeholder data with actual data from a MongoDB database.
####Installing MongoDB
To install MongoDB on your specific platform, refer to the MongoDB QuickStart. Here are some quick steps to install MongoDB on a Mac:
Open a terminal window and type the following command to download the latest release: curl http://downloads.mongodb.org/osx/mongodb-osx-x86_64-2.2.0.tgz > ~/Downloads/mongo.tgz
Note: You may need to adjust the version number. 2.2.0 is the latest production version at the time of this writing.
Extract the files from the mongo.tgz archive: cd ~/Downloads tar -zxvf mongo.tgz
Move the mongo folder to /usr/local (or another folder according to your personal preferences): sudo mv -n mongodb-osx-x86_64-2.2.0/ /usr/local/
(Optional) Create a symbolic link to make it easier to access: sudo ln -s /usr/local/mongodb-osx-x86_64-2.2.0 /usr/local/mongodb
Create a folder for MongoDB’s data and set the appropriate permissions:
sudo mkdir -p /data/db
sudo chown id -u /data/db
Start mongodb cd /usr/local/mongodb ./bin/mongod
You can also open the MongoDB Interactive Shell in another terminal window to interact with your database using a command line interface. cd /usr/local/mongodb ./bin/mongo
Refer to the MongoDB Interactive Shell documentation for more information.
####Installing the MongoDB Driver for Node.js
There are different solutions offering different levels of abstraction to access MongoDB from Node.js (For example, Mongoose and Mongolia). A comparaison of these solutions is beyond the scope of this article. In this, guide we use the native Node.js driver.
To install the the native Node.js driver, open a terminal window, cd to your nodecellar folder, and execute the following command:
`npm install mongodb
Implementing the REST API
The full REST API for the nodecellar application consists of the following methods:
Method URL Action GET /wines Retrieve all wines GET /wines/5069b47aa892630aae000001 Retrieve the wine with the specified _id POST /wines Add a new wine PUT /wines/5069b47aa892630aae000001 Update wine with the specified _id DELETE /wines/5069b47aa892630aae000001 Delete the wine with the specified _id To implement all the routes required by the API, modify server.js as follows:
var express = require('express'),
wine = require('./routes/wines');
var app = express();
app.configure(function () {
app.use(express.logger('dev')); /* 'default', 'short', 'tiny', 'dev' */
app.use(express.bodyParser());
});
app.get('/wines', wine.findAll);
app.get('/wines/:id', wine.findById);
app.post('/wines', wine.addWine);
app.put('/wines/:id', wine.updateWine);
app.delete('/wines/:id', wine.deleteWine);
app.listen(3000);
console.log('Listening on port 3000...');
var mongo = require('mongodb');
var Server = mongo.Server,
Db = mongo.Db,
BSON = mongo.BSONPure;
var server = new Server('localhost', 27017, {auto_reconnect: true});
db = new Db('winedb', server);
db.open(function(err, db) {
if(!err) {
console.log("Connected to 'winedb' database");
db.collection('wines', {strict:true}, function(err, collection) {
if (err) {
console.log("The 'wines' collection doesn't exist. Creating it with sample data...");
populateDB();
}
});
}
});
exports.findById = function(req, res) {
var id = req.params.id;
console.log('Retrieving wine: ' + id);
db.collection('wines', function(err, collection) {
collection.findOne({'_id':new BSON.ObjectID(id)}, function(err, item) {
res.send(item);
});
});
};
exports.findAll = function(req, res) {
db.collection('wines', function(err, collection) {
collection.find().toArray(function(err, items) {
res.send(items);
});
});
};
exports.addWine = function(req, res) {
var wine = req.body;
console.log('Adding wine: ' + JSON.stringify(wine));
db.collection('wines', function(err, collection) {
collection.insert(wine, {safe:true}, function(err, result) {
if (err) {
res.send({'error':'An error has occurred'});
} else {
console.log('Success: ' + JSON.stringify(result[0]));
res.send(result[0]);
}
});
});
}
exports.updateWine = function(req, res) {
var id = req.params.id;
var wine = req.body;
console.log('Updating wine: ' + id);
console.log(JSON.stringify(wine));
db.collection('wines', function(err, collection) {
collection.update({'_id':new BSON.ObjectID(id)}, wine, {safe:true}, function(err, result) {
if (err) {
console.log('Error updating wine: ' + err);
res.send({'error':'An error has occurred'});
} else {
console.log('' + result + ' document(s) updated');
res.send(wine);
}
});
});
}
exports.deleteWine = function(req, res) {
var id = req.params.id;
console.log('Deleting wine: ' + id);
db.collection('wines', function(err, collection) {
collection.remove({'_id':new BSON.ObjectID(id)}, {safe:true}, function(err, result) {
if (err) {
res.send({'error':'An error has occurred - ' + err});
} else {
console.log('' + result + ' document(s) deleted');
res.send(req.body);
}
});
});
}
/*--------------------------------------------------------------------------------------------------------------------*/
// Populate database with sample data -- Only used once: the first time the application is started.
// You'd typically not find this code in a real-life app, since the database would already exist.
var populateDB = function() {
var wines = [
{
name: "CHATEAU DE SAINT COSME",
year: "2009",
grapes: "Grenache / Syrah",
country: "France",
region: "Southern Rhone",
description: "The aromas of fruit and spice...",
picture: "saint_cosme.jpg"
},
{
name: "LAN RIOJA CRIANZA",
year: "2006",
grapes: "Tempranillo",
country: "Spain",
region: "Rioja",
description: "A resurgence of interest in boutique vineyards...",
picture: "lan_rioja.jpg"
}];
db.collection('wines', function(err, collection) {
collection.insert(wines, {safe:true}, function(err, result) {});
});
};
Restart the server to test the API.
Testing the API using cURL
If you want to test your API before using it in a client application, you can invoke your REST services straight from a browser address bar. For example, you could try:
http://localhost:3000/wines You will only be able to test your GET services that way. A more versatile solution to test RESTful services is to use cURL, a command line utility for transferring data with URL syntax.
For example, using cURL, you can test the Wine Cellar API with the following commands:
Get all wines: curl -i -X GET http://localhost:3000/wines
Get wine with _id value of 5069b47aa892630aae000007 (use a value that exists in your database): curl -i -X GET http://localhost:3000/wines/5069b47aa892630aae000007
Delete wine with _id value of 5069b47aa892630aae000007: curl -i -X DELETE http://localhost:3000/wines/5069b47aa892630aae000007
Add a new wine: curl -i -X POST -H 'Content-Type: application/json' -d '{"name": "New Wine", "year": "2009"}' http://localhost:3000/wines
Modify wine with _id value of 5069b47aa892630aae000007: curl -i -X PUT -H 'Content-Type: application/json' -d '{"name": "New Wine", "year": "2010"}' http://localhost:3000/wines/5069b47aa892630aae000007
i have the same code
var express = require('express');
var bodyParser = require('body-parser');
var app = express();
app.use(bodyParser.urlencoded({extended:false}))
app.use(bodyParser.json());
but i get the message : app.use is not a function.
please, help me