Node.js MongoDB Query
Thursday 28 June 2018
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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":
var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, function(err, db) {
if (err) throw err;
var dbo = db.db("mydb");
var 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.js
Which 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":
var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, function(err, db) {
if (err) throw err;
var dbo = db.db("mydb");
var 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.js
Which will give you this result:
[
{ _id: 58fdbf5c0ef8a50b4cdd9a8b , name: 'Richard', address: 'Sky st 331' },
{ _id: 58fdbf5c0ef8a50b4cdd9a91 , name: 'Viola', address: 'Sideway 1633' }
]
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