Mongoose | where() Function

The where() function is used to create a Query, applies the passed conditions and returns the Query.

Installation of mongoose module:

1. You can visit the link to Install mongoose module. You can install this package by using this command.

   npm install mongoose

2. After installing mongoose module, you can check your mongoose version in command prompt using the command.

   npm version mongoose

3. After that, you can create a folder and add a file, for example index.js. To run this file you need to run the following command.

   node index.js

Filename: index.js

• const mongoose = require('mongoose');
  
  // Database Connection
  mongoose.connect('mongodb://127.0.0.1:27017/geeksforgeeks', {
      useNewUrlParser: true,
      useCreateIndex: true,
      useUnifiedTopology: true
  });
  
  // User model
  const User = mongoose.model('User', {
      name: { type: String },
      age: { type: Number }
  });
  
  User.where('age').gte(5).lte(200)
          .exec(function (err, result) {
      if (err){
          console.log(err)
      }else{
          console.log("Result :", result)
      }
  });

Steps to run the program:

1. The project structure will look like this:
   
2. Make sure you have installed mongoose module using following command:

   npm install mongoose

3. Below is the sample data in the database before the function is executed, You can use any GUI tool or terminal to see the database, like we have used Robo3T GUI tool as shown below:
   
4. Run index.js file using below command:

   node index.js

   

So this is how you can use the mongoose where() function which creates a Query, applies the passed conditions, and returns the Query.