Mongoose Schematype.get() API

Mongoose is a MongoDB object modeling and handling for a node.js environment. The Schematype.get() method of the Mongoose API is used to get the manipulate or transform data from MongoDB database or Schema. Using this function we can modify the value of any attribute in the database based on our requirement. Let us understand Mongoose Schematype.get() method using example.

Syntax:

SchemaType.get(<function>)

Parameters: The Schematype.get() method accepts a single parameter:

• getterFunction: It is the function that return the modified or manipulated data.

Return Value: The Schematype.get() function returns access to all the instances of this schema type. 

Setting up Node.js application:

Step 1: Create a Node.js application using the following command:

npm init

Step 2: After creating the NodeJS application, Install the required module using the following command:

npm install mongoose

Project Structure: The project structure will look like this:

Database Structure: The database structure will look like this, the following documents are present in the collection.

Example 1: In this example, We have established a database connection using mongoose and defined model over userSchema, having three columns or fields “name”, “age”, and “weight”. At the schema level on “weight” attribute we have defined getter function that will return round up value of “weight”.

Filename: app.js

Javascript

// Require mongoose module
const mongoose = require("mongoose");

// Set Up the Database connection
mongoose.connect("mongodb://localhost:27017/geeksforgeeks", {
    useNewUrlParser: true,
    useUnifiedTopology: true,
});

// Define a user schema
const userSchema = new mongoose.Schema({
    name: {
        type: String
    },
    age: {
        type: Number
    },
    weight: {
        type: Number,
        get: (value) => {
            return Math.ceil(value)
        }
    }
});

const User = mongoose.model('User', userSchema);

// Find the user by given ID
User.findById('63845defc7553ff921623ff9').then(result => {
    console.log(result.weight);
});

Step to run the program: To run the application execute the below command from the root directory of the project:

node app.js

Output:

66

Example 2: In this example, We have established a database connection using mongoose and defined a model over userSchema, having four columns or fields “name”, “age”, “weight”, and “height”. At the schema level on the “height” attribute, we have defined getter function that will return height in centimeter.

Filename: app.js

Javascript

// Require mongoose module
const mongoose = require("mongoose");

// Set Up the Database connection
mongoose.connect("mongodb://localhost:27017/geeksforgeeks", {
    useNewUrlParser: true,
    useUnifiedTopology: true,
});

// Define the user schema
const userSchema = new mongoose.Schema({
    name: {
        type: String
    },
    age: {
        type: Number
    },
    weight: {
        type: Number,
        get: (value) => {
            return Math.ceil(value)
        }
    },
    height: {
        type: Number,

        // Define the getter function
        get: (value) => {
            return value * 30.48
        }
    }
});

const User = mongoose.model('User', userSchema);

const user = new User({
    name: "User1", age: 25,
    weight: 68.5, height: 5.8
})
user.save()
console.log('Height in cm -', user.height)

Step to run the program: To run the application execute the below command from the root directory of the project:

node app.js

Output:

Height in cm - 176.784

Reference: https://mongoosejs.com/docs/api/schematype.html#schematype_SchemaType-get