Product.ts

import { Schema, model } from 'mongoose'

// Utility type which you can put in your utils file
type ID = Schema.Types.ObjectId

export interface IProduct {
    // Optional so it is easier to use when trying to create a new document
    _id?: ID
    name: string
    price: number
    stock: number
} 

// Here we use ProductSchema as a type generic for the schema definition, this will check the structure of the schema but not the types of the schema
const productSchema = new Schema<IProduct>({
    name: String,
    price: Number,
    stock: Number
})

// Here we use ProductSchema as a type generic for the model to type the resulted documents of the queries on the model.
export const Product = model<IProduct>('Product', productSchema)