Mongoose Query.prototype.in() API

The Mongoose Query API in() method is used to scan all the documents in a collection and return those whose path values lie in the array that is passed in the method’s argument.

Syntax:

Query.prototype.in(path, val)

Parameters: It accepts the following parameters as mentioned above and described below:

• path: It is a string that identifies the attribute name in the mongoose schema
• val: It is an array that determines the range of values to scan and find all the documents whose paths have values lying in the array

Return type: It returns a Query object as a response.

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 completing the Node.js application, Install the required module using the following command:

npm install mongoose

Example 1: In this example, we will use this method to return documents whose age lies in the values “[35, 40]”

Filename: main.js

Javascript

//Importing the module
const mongoose = require('mongoose')

// Creating the 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'));

let personSchema = new mongoose.Schema({
    name: {
        type: String,
    },
    age: {
        type: Number,
    }
});

let personsArray = [
    {
        name: 'Luffy',
        age: 20
    },
    {
        name: 'Nami',
        age: 20,
    },
    {
        name: 'Zoro',
        age: 35
    }
]

let Person = mongoose.model('Person', personSchema);

(async () => {
    await Person.insertMany(personsArray)
    const res = await Person.find().in('age', [35, 40])
    console.log({ res });
})();

Step to Run Application: Run the application using the following command from the root directory of the project:

node main.js

Output: 

GUI Representation of the  Database using MongoDB Compass:

Example 2: In this example, we will use this method to return documents whose name lies in the values “[“Zoro”, “Usorp”]”

Filename: main.js

Javascript

//Importing the module
const mongoose = require('mongoose')

// Creating the 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'));

let personSchema = new mongoose.Schema({
    name: {
        type: String,
    },
    age: {
        type: Number,
    }
});

let personsArray = [
    {
        name: 'Luffy',
        age: 20
    },
    {
        name: 'Nami',
        age: 20,
    },
    {
        name: 'Zoro',
        age: 35
    }
]

let Person = mongoose.model('Person', personSchema);

(async () => {
    await Person.insertMany(personsArray)
    const res = await Person.find().in(
        'name', ['Zoro', 'Usorp']
    )
    console.log({ res });
})();

Step to Run Application: Run the application using the following command from the root directory of the project:

node main.js

Output:

GUI Representation of the  Database using MongoDB Compass:

Reference: https://mongoosejs.com/docs/api/query.html#query_Query-in