Filter the Result
When finding documents in a collection, you can filter the result by using a query object.
The first argument of the find() method is a query object, and is used to limit the search.
Example
Find documents with the address "Park Lane 38":
let MongoClient = require('mongodb').MongoClient;
let url = "mongodb://localhost:27017/";
MongoClient.connect(url, function(err, db) {
if (err) throw err;
let dbo = db.db("mydb");
let query = { address: "Park Lane 38" };
dbo.collection("customers").find( query ).toArray(function(err, result) {
if (err) throw err;
console.log(result);
db.close();
});
});Save the code above in a file called "demo_mongodb_query.js" and run the file:
Run "demo_mongodb_query.js"
C:\Users\
Your Name
>node demo_mongodb_query.jsWhich will give you this result
[ { _id: 58fdbf5c0ef8a50b4cdd9a8e , name: 'Ben', address: 'Park Lane 38' }
]Filter With Regular Expressions
You can write regular expressions to find exactly what you are searching for.
Regular expressions can only be used to query strings .
To find only the documents where the "address" field starts with the letter "S", use the regular expression /^S/ :
Example
Find documents where the address starts with the letter "S":
let MongoClient = require('mongodb').MongoClient;
let url = "mongodb://localhost:27017/";
MongoClient.connect(url, function(err, db) {
if (err) throw err;
let dbo = db.db("mydb");
let query = { address: /^S/ };
dbo.collection("customers").find(query).toArray(function(err, result) {
if (err) throw err;
console.log(result);
db.close();
});
});Save the code above in a file called "demo_mongodb_query_s.js" and run the file:
Run "demo_mongodb_query_s.js"
C:\Users\
Your Name
>node demo_mongodb_query_s.jsWhich will give you this result
[ { _id: 58fdbf5c0ef8a50b4cdd9a8b , name: 'Richard', address: 'Sky st 331' }, { _id: 58fdbf5c0ef8a50b4cdd9a91 , name: 'Viola', address: 'Sideway 1633' }
]