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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:
_id: new ObjectId(“616d7984ab589958610e0257”),
name: ‘abc’,
address: ‘India’
}
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:
{
_id: new ObjectId(“616d7984ab589958610e0257”),
name: ‘abc’,
address: ‘India’
},
_id: new ObjectId(“616d7ac3895eb21861a35ad0”),
name: ‘xyz’,
address: ‘delhi’
}
]
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:
{
_id: new ObjectId(“616d7984ab589958610e0257”),
name: ‘abc’,
address: ‘India’
}
]
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:
{
_id:1,
Schoolname:Abc delhi,studentdetails:
{
_id: new ObjectId(“616d7984ab589958610e0257”),
name: ‘abc’,
address: ‘India’,
}
}
]
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.