How does Query.prototype.lt() work in Mongoose ?
The Query.prototype.lt() function is used to specify a $lt query condition. It returns documents that are less than the specified condition.
Syntax:
Query.prototype.lt()
Parameters: This function has val parameter and an optional path parameter.
Return Value: This function returns Query Object.
Mongoose Installation:
npm install mongoose
After installing the mongoose module, you can check your mongoose version in command prompt using the command.
npm mongoose --version
After that, you can just create a folder and add a file for example, index.js as shown below.
Database: The sample database used here is shown below:
Example 1:
index.js
const mongoose = require( 'mongoose' ); // Database connection mongoose.connect( 'mongodb://127.0.0.1:27017/w3wiki' , { useNewUrlParser: true , useCreateIndex: true , useUnifiedTopology: true }); // User model const User = mongoose.model( 'User' , { name: { type: String }, age: { type: Number } }); var query = User.find() query.where( 'age' ).lt(10).exec( function (err, res){ if (err) console.log(err.message) else console.log(res) }); |
The project structure will look like this:
Run index.js file using below command:
node index.js
Output:
[ { _id: 5ebc367da99bde77b2efb9bf, name: ‘Piyush’, age: 5, __v: 0 } ]
Example 2:
index.js
const express = require( 'express' ); const mongoose = require( 'mongoose' ); const app = express() // Database connection mongoose.connect( 'mongodb://127.0.0.1:27017/w3wiki' , { useNewUrlParser: true , useCreateIndex: true , useUnifiedTopology: true }); // User model const User = mongoose.model( 'User' , { name: { type: String }, age: { type: Number } }); var query = User.find() query.where( 'age' ).lt(25).exec( function (err, res){ if (err) console.log(err.message) else console.log(res) }); app.listen(3000, function (error ) { if (error) console.log(error) console.log( "Server listening on PORT 3000" ) }); |
The project structure will look like this:
Run index.js file using below command:
node index.js
Output:
Server listening on PORT 3000
[
{ _id: 5ebb9129a99bde77b2efb809, name: ‘Gourav’, age: 10, __v: 0 },
{ _id: 5ebc367da99bde77b2efb9bf, name: ‘Piyush’, age: 5, __v: 0 }
]
Reference: https://mongoosejs.com/docs/api/query.html#query_Query-lt