Node.js MongoDB Tutorial

In this article, we will see how we can use the mongo db database with node js. We will look at how to create a database, connect databases, create a collection and other methods with code and examples.

Install MongoDB:

To install MongoDB on your device run the below command:

Npm install mongodb.

Connecting to mongodb?

To connect with mongo db we will use the connect method.

Code for connecting to mongodb:

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/dataflair";
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
});

Creating database:

To create a database, we will use a MongoClient object. We will pass a connection URL and the name of the database. If it does not exist, MongoDB will create the database, and connect to it.

Code for Creating database:

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/dataflair";
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    console.log("Database created!");
    db.close();
});

Output:

Creating collection:

We will use the create collection method to create a collection.

Code for Creating collection:

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    var dbo = db.db("dataflair");
    dbo.createCollection("students", function (err, res) {
        if (err) throw err;
        console.log("Collection created!");
        db.close();
    });
});

Output:

Inserting into collection:

We will use the insert one method to insert into the collection.

Code for inserting:

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    var dbo = db.db("dataflair");
    var obj = { name: "abc", address: "India" };
    dbo.collection("students").insertOne(obj, function (err, res) {
        if (err) throw err;
        console.log("1 document inserted!");
        db.close();
    });
});

Output:

MongoDB Find query:

To find a particular document in mongodb, we use the find method.

Code for find()

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
 
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    var dbo = db.db("dataflair");
 
 
    dbo.collection("students").findOne({}, function (err, res) {
        if (err) throw err;
        console.log(res);
        db.close();
    });
});

Output:

MongoDB Filter result :

We will use the find method and pass the query as the first argument to it.

Code for filtering the result:

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
 
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    var dbo = db.db("dataflair");
    var query = { address: "India" };
    dbo.collection("students").find(query).toArray(function (err, res) {
        if (err) throw err;
        console.log(res);
        db.close();
    });
});

Output

MongoDB Sort Function:

To sort the data in some order, use the sort function.

Code for sorting

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
 
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    var dbo = db.db("dataflair");
    dbo.collection("students").find().sort({ name: 1 }).toArray(function (err, res) {
        if (err) throw err;
        console.log(res);
        db.close();
    });
});

Output:

MongoDB Limit Function:

To get a fixed amount of information, we limit the result by using the limit function.

Code for limit:

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
 
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    var dbo = db.db("dataflair");
    dbo.collection("students").find().limit(1).toArray(function (err, res) {
        if (err) throw err;
        console.log(res);
        db.close();
    });
});

Output:

MongoDB Deleting document:

We will use the delete one method to delete a single document. To delete multiple documents, use the delete many method.

Code for deleting documents:

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
 
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    var dbo = db.db("dataflair");
    var query = { address: "India" };
    dbo.collection("students").deleteOne(query, function (err, res) {
        if (err) throw err;
        console.log("1 item deleted");
        db.close();
    });
});

Output:

MongoDB Join Method:

In order to join two collections, we use the join method.

Code for join

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
 
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    var dbo = db.db("dataflair");
    dbo.collection("schools").aggregate([
        {
            $lookup:
            {
                from: 'students',
                localField: '_id',
                foreignField: '_id',
                as: 'studentdetails'
            }
        }
    ]).toArray(function (err, res) {
        if (err) throw err;
        console.log(res);
        db.close();
    });
});

Output:

MongoDB Dropping collection:

We will use the drop() method to delete a collection;

Code for dropping collection:

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
 
MongoClient.connect(url, function (err, db) {
    if (err) throw err;
    var dbo = db.db("dataflair");
    var query = { address: "India" };
    dbo.collection("students").drop(function (err, res) {
        if (err) throw err;
        console.log("collection deleted");
        db.close();
    });
});

Output:

Conclusion:

We hope you were able to learn using mongodb with node js. Do check the DataFlair website for other amazing articles.