Importing a custom mongoose schema in another schema - node.js

Question

My software has a mongoose Schema, let's call it carSchema, and I am exporting a model of the carSchema called Car. Example:
/* Car.js */
var carSchema= new Schema({
_id: Schema.Types.ObjectId,
type: String,
wheels: Number
});
carSchema.statics.drive = async function(){
...
}
module.exports = mongoose.model('Car', carSchema);
Now say my software has another schema called lotSchema in another file, that uses carSchema in it:
/* Lot.js */
var lotSchema = new Schema({
_id: Schema.Types.ObjectId,
carArr: [carSchema]
});
lotSchema.statics.getAllId = async function(){
return carSchema[0]['_id']
}
How can I properly import or export carSchema for use in lotSchema? Would a simple const carSchema = require('Car.js') suffice?

Answer 1

If you are not using not using es6/7 then you can do this
/* Car.js */
const carSchema= new Schema({
_id: Schema.Types.ObjectId,
type: String,
wheels: Number
});
carSchema.statics.drive = async function(){
...
}
module.exports.carSchema = carSchema;
module.exports.carModel = mongoose.model('Car', carSchema);
/* Lot.js */
const { carSchema , carModel } = require('./Car.js');
var lotSchema = new Schema({
_id: Schema.Types.ObjectId,
carArr: [carSchema]
});
lotSchema.statics.getAllId = async function(){
return carSchema[0]['_id']
}

Answer 2

You could do this in Car.js
module.exports = {
useCarSchema: function(myCollection) {
return mongoose.model('Car', carSchema, myCollection);
}
}
And this in Lot.js
var carSchema = require('./Car.js');
var Car = carSchema.useCarSchema(myCollection);

Answer 3

You can use Populate:
Population is the process of automatically replacing the specified
paths in the document with document(s) from other collection(s). We
may populate a single document, multiple documents, plain object,
multiple plain objects, or all objects returned from a query.
Example:
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const carSchema= new Schema({
_id: Schema.Types.ObjectId,
type: String,
wheels: Number
});
const lotSchema = new Schema({
_id: Schema.Types.ObjectId,
cars: [{ type: Schema.Types.ObjectId, ref: 'Car' }]
});
mongoose.model('Car', carSchema);
mongoose.model('Lot', lotSchema);
Now, to populate works, you first need to create a car object car = new Car({}) and a lot object lot = new Lot({}), and then:
lot.cars.push(car);
lot.save(callback);