how to create alias in populate moongoose + nodejs

To create an alias in Mongoose using Node.js, you can follow these steps:

1. Define the schema for the main model and the referenced model.
2. Use the ref option in the schema to specify the referenced model.
3. Create a virtual property in the main model's schema using the populate() method.
4. Use the virtual property to define the alias for populating the referenced model.

Here's an example of how you might implement this:

const mongoose = require('mongoose');

// Define the schema for the referenced model
const referencedSchema = new mongoose.Schema({
  // ...define the fields for the referenced model
});

// Define the schema for the main model
const mainSchema = new mongoose.Schema({
  referencedModel: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Referenced', // Specify the referenced model
  }
});

// Create a virtual property in the main model's schema
mainSchema.virtual('aliasName', {
  ref: 'Referenced', // Use the referenced model
  localField: 'referencedModel', // Define the local field
  foreignField: '_id', // Define the foreign field
  justOne: true, // Set the option to populate only one document
});

// Create the main model using the schema
const MainModel = mongoose.model('Main', mainSchema);

// Use the virtual property to populate the referenced model with the alias
MainModel.find().populate('aliasName').exec((err, docs) => {
  // ...handle the populated documents
});

This approach allows you to create an alias for populating the referenced model in Mongoose using Node.js.