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  • Quick Start

Quick Start

This guide will show you how to set up a simple application using Node.js and MongoDB. Its scope is only how to set up the driver and perform the simple CRUD operations. For more in-depth coverage, see the tutorials.

Create the package.json file

First, create a directory where your application will live.

mkdir myproject
cd myproject

Enter the following command and answer the questions to create the initial structure for your new project:

npm init

Next, install the driver dependency.

npm install mongodb --save

You should see NPM download a lot of files. Once it’s done you’ll find all the downloaded packages under the node_modules directory.

Start a MongoDB Server

For complete MongoDB installation instructions, see the manual.

  1. Download the right MongoDB version from MongoDB
  2. Create a database directory (in this case under /data).
  3. Install and start a mongod process.
mongod --dbpath=/data

You should see the mongod process start up and print some status information.

Connect to MongoDB

Create a new app.js file and add the following code to try out some basic CRUD operations using the MongoDB driver.

Add code to connect to the server and the database myproject:

var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';

// Use connect method to connect to the server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  db.close();
});

Run your app from the command line with:

node app.js

The application should print Connected successfully to server to the console.

Insert a Document

Add to app.js the following function which uses the insertMany method to add three documents to the documents collection.

var insertDocuments = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Insert some documents
  collection.insertMany([
    {a : 1}, {a : 2}, {a : 3}
  ], function(err, result) {
    assert.equal(err, null);
    assert.equal(3, result.result.n);
    assert.equal(3, result.ops.length);
    console.log("Inserted 3 documents into the collection");
    callback(result);
  });
}

The insert command returns an object with the following fields:

  • result Contains the result document from MongoDB
  • ops Contains the documents inserted with added _id fields
  • connection Contains the connection used to perform the insert

Add the following code to call the insertDocuments function:

var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  insertDocuments(db, function() {
    db.close();
  });
});

Run the updated app.js file:

node app.js

The operation returns the following output:

Connected successfully to server
Inserted 3 documents into the collection

Find All Documents

Add a query that returns all the documents.

var findDocuments = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Find some documents
  collection.find({}).toArray(function(err, docs) {
    assert.equal(err, null);
    console.log("Found the following records");
    console.log(docs)
    callback(docs);
  });
}

This query returns all the documents in the documents collection. Add the findDocument method to the MongoClient.connect callback:

var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected correctly to server");

  insertDocuments(db, function() {
    findDocuments(db, function() {
      db.close();
    });
  });
});

Find Documents with a Query Filter

Add a query filter to find only documents which meet the query criteria.

var findDocuments = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Find some documents
  collection.find({'a': 3}).toArray(function(err, docs) {
    assert.equal(err, null);
    console.log("Found the following records");
    console.log(docs);
    callback(docs);
  });      
}

Only the documents which match 'a' : 3 should be returned.

Update a document

The following operation updates a document in the documents collection.

var updateDocument = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Update document where a is 2, set b equal to 1
  collection.updateOne({ a : 2 }
    , { $set: { b : 1 } }, function(err, result) {
    assert.equal(err, null);
    assert.equal(1, result.result.n);
    console.log("Updated the document with the field a equal to 2");
    callback(result);
  });  
}

The method updates the first document where the field a is equal to 2 by adding a new field b to the document set to 1. Next, update the callback function from MongoClient.connect to include the update method.

var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  insertDocuments(db, function() {
    updateDocument(db, function() {
      db.close();
    });
  });
});

Remove a document

Remove the document where the field a is equal to 3.

var removeDocument = function(db, callback) {
  // Get the documents collection
  var collection = db.collection('documents');
  // Delete document where a is 3
  collection.deleteOne({ a : 3 }, function(err, result) {
    assert.equal(err, null);
    assert.equal(1, result.result.n);
    console.log("Removed the document with the field a equal to 3");
    callback(result);
  });    
}

Add the new method to the MongoClient.connect callback function.

var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  insertDocuments(db, function() {
    updateDocument(db, function() {
      removeDocument(db, function() {
        db.close();
      });
    });
  });
});

Index a Collection

Indexes can improve your application’s performance. The following function creates an index on the a field in the documents collection.

var indexCollection = function(db, callback) {
  db.collection('documents').createIndex(
    { "a": 1 },
      null,
      function(err, results) {
        console.log(results);
        callback();
    }
  );
};

Add the indexCollection method to your app:

var MongoClient = require('mongodb').MongoClient
  , assert = require('assert');

// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the server
MongoClient.connect(url, function(err, db) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  insertDocuments(db, function() {
    indexCollection(db, function() {
      db.close();
    });
  });
});

For more detailed information, see the tutorials.

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