Mongoose Document Model.prototype.model() API

The Mongoose Document API Model.prototype.model() method of the Mongoose API is used on the Document model. It allows to get the model instance. We can call this method on any model object and by providing another model name to the method parameter we will get the new instance of that model. Let us understand the model() method using an example.

Syntax:

document.model( model );

Parameters: This method accepts a single parameter as discussed below:

• model: It is used to specify the name of the model.

Return Value: This method return the new instance of model, we send as a parameter to the method.

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 are illustrating the functionality of model() method. We have defined a DUMMYMODEL, using the object of dummymodel we are creating new instance of Customer model and at the end fetching one record from the database.

Filename: app.js

Javascript

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

// Set Up the Database connection
const URI = "mongodb://localhost:27017/geeksforgeeks";

const connectionObject = mongoose.createConnection(URI, {
    useNewUrlParser: true,
    useUnifiedTopology: true,
});

const Customer = connectionObject.model(
    "Customer",
    new mongoose.Schema({
        name: String,
        address: String,
        orderNumber: Number,
    })
);

const DUMMYMODEL = connectionObject.model(
    "DUMMYMODEL",
    new mongoose.Schema({
        name: String,
    })
);

const doc = new DUMMYMODEL();
doc.$model("Customer").find({ name: "Chintu" }).then(res => {
    console.log(res);
}).catch(err => {
    console.log(err);
});

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

node app.js

Output:

[
  {
    _id: new ObjectId("639ede899fdf57759087a655"),
    name: 'Chintu',
    address: 'IND',
    orderNumber: 9,
    __v: 0
  }
]

Example 2: In this example, we are illustrating the functionality of model() method. At the end, we are comparing the newly instantiated object with original Customer model. 

Filename: app.js

Javascript

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

// Set Up the Database connection
const URI = "mongodb://localhost:27017/geeksforgeeks";

const connectionObject = mongoose.createConnection(URI, {
    useNewUrlParser: true,
    useUnifiedTopology: true,
});

const Customer = connectionObject.model(
    "Customer",
    new mongoose.Schema({
        name: String,
        address: String,
        orderNumber: Number,
    })
);

const DUMMYMODEL = connectionObject.model(
    "DUMMYMODEL",
    new mongoose.Schema({
        name: String,
    })
);

const doc = new DUMMYMODEL();
const newInstance = doc.$model("Customer")
console.log(newInstance.modelName === Customer.modelName);

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

node app.js

Output:

true

Reference: https://mongoosejs.com/docs/api/model.html#model_Model-model