MongoDB Filter Query

The find() method is also used to filter the result on a specific parameter. You can filter the result by using a query object.

Example

Filter the records to retrieve the specific employee whose address is “Delhi”.

Create a js file named “query1.js”, having the following code:

var http = require('http');  

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

var url = "mongodb://localhost:27017/MongoDatabase";  

MongoClient.connect(url, function(err, db) {  

if (err) throw err;  

var query = { address: "Delhi" };  

db.collection("employees").find(query).toArray(function(err, result) {  

if (err) throw err;  

console.log(result);  

db.close();  

});  

});  

Open the command terminal and run the following command:

Node query1.js  

Node.js MongoDB Filter With Regular Expression

You can also use regular expression to find exactly what you want to search. Regular expressions can be used only to query strings.

Example

Retrieve the record from the collection where address start with letter “L”.

Create a js file named “query2”, having the following code:

var http = require('http');  

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

var url = "mongodb://localhost:27017/MongoDatabase";  

MongoClient.connect(url, function(err, db) {  

if (err) throw err;  

var query = { address: /^L/ };  

db.collection("employees").find(query).toArray(function(err, result) {  

if (err) throw err;  

console.log(result);  

db.close();  

});  

});

Open the command terminal and run the following command:

Node query2.js