Mongoose Query prototype.where() API
Last Updated :
26 Apr, 2025
Mongoose is a MongoDB object modeling and handling for a node.js environment. Mongoose Query where() method is used to filter the documents from a collection using the MongoDB query system. It can be used in various ways, like chaining or passing query conditions. Let's understand more about this with some examples.
Syntax:
Query.prototype.where()
Parameters: It accepts 2 parameters that are described below::
- path: It is of type String or Object.
- val: It can be of any type.
Return type: It returns the Query object.
Creating node application And Installing Mongoose:
Step 1: Create a node application using the following command:
mkdir folder_name
cd folder_name
npm init -y
touch main.js
Step 2: After creating the ReactJS application, Install the required module using the following command:
npm install mongoose
Project Structure: It will look like the following.
GUI Representation of the Database using MongoDB Compass: Currently, the collection has no data.
Example 1: In this example, we will use Query where() method to filter out the documents using the chaining method where we would chain different queries together.
Filename: main.js
JavaScript
const mongoose = require('mongoose')
// Database connection
mongoose.connect('mongodb://localhost:27017/query-helpers', {
dbName: 'event_db',
useNewUrlParser: true,
useUnifiedTopology: true
}, err => err ? console.log(err) :
console.log('Connected to database'));
const personSchema = new mongoose.Schema({
name: {
type: String,
},
age: {
type: Number,
}
});
const personsArray = [
{
name: 'John',
age: 22
},
{
name: 'Dave',
age: 17
},
{
name: 'Earl',
age: 12
}
]
const Person = mongoose.model('Person', personSchema);
(async () => {
await Person.insertMany(personsArray);
const persons =
await Person.find().where('age').gte(18);
console.log(persons);
})()
Step to Run Application: Run the application using the following command from the root directory of the project:
node main.js
Output: We see that the value remains unchanged in the result.
GUI Representation of the Database using MongoDB Compass:
Example 2: In this example, we will use Query API where() method to filter out the documents by passing query conditions as the argument to the where() method.
Filename: main.js
JavaScript
const mongoose = require('mongoose')
// Database connection
mongoose.connect('mongodb://localhost:27017/query-helpers', {
dbName: 'event_db',
useNewUrlParser: true,
useUnifiedTopology: true
}, err => err ? console.log(err) :
console.log('Connected to database'));
const personSchema = new mongoose.Schema({
name: {
type: String,
},
age: {
type: Number,
}
});
const personsArray = [
{
name: 'John',
age: 22
},
{
name: 'Dave',
age: 17
},
{
name: 'Earl',
age: 12
}
]
const Person = mongoose.model('Person', personSchema);
(async () => {
await Person.insertMany(personsArray);
const persons = await Person.find().where
({ age: { $lte: 18 } })
console.log(persons);
})()
Step to Run Application: Run the application using the following command from the root directory of the project:
node main.js
Output: We see that the value remains unchanged in the result.
GUI Representation of the Database using MongoDB Compass:
Reference: https://mongoosejs.com/docs/api/query.html#query_Query-where