Typegoose without extending

buildModel.ts

// If you want to use Mongoose with TypeScript, you are in trouble.
// Typegoose comes to the rescue, but it requires model classes to extend Typegoose class,
// which breaks using model classes as interfaces for casting in your code

// Here is the solution: don't extend Typegoose and use this function to create your models:

import {InstanceType, Typegoose} from 'typegoose'
import {Connection, Model} from 'mongoose'

function buildModel<T, U>(constructor: {new (): T} & U, db: Connection, collectionName: string): Model<InstanceType<T>> & U {
    const instance = new constructor() as any;
    instance.buildSchema = (Typegoose.prototype as any).buildSchema;
    return Typegoose.prototype.setModelForClass.call(instance, constructor, {
        existingConnection: db, schemaOptions: {collection: collectionName}
    }) as any;
}

// This is hacky, and I wish Typegoose could include something like this by default instead of a base class