mm-graphql/models.js

const MongoClient = require("mongodb").MongoClient;
const ObjectID    = require("mongodb").ObjectID;
const {connect}          = require('mm')

module.exports = async (dbName='shop') => {
    const {Savable, slice} = await connect(dbName)

    async function getModels(id){
        const SlicedSavable = slice([id, 'user', 'admin'])

        class User extends SlicedSavable {
            constructor(...params){
                super(...params)
                this.orders = this.orders instanceof Array ? this.orders : (this.orders ? [this.orders] : []) 
            }

            static get relations(){
                return {
                    orders: "user"
                }
            }
        }
        SlicedSavable.addClass(User)

        class Good extends SlicedSavable {
            constructor(...params){
                super(...params)
                this.categories = this.category instanceof Array ? this.category : (this.category ? [this.category] : []) 
                this.orderGoods = this.orderGoods instanceof Array ? this.orderGoods : (this.orderGoods ? [this.orderGoods] : []) 
            }

            static get relations(){
                return {
                    categories: "goods",
                    orderGoods: "good",
                }
            }
        }
        SlicedSavable.addClass(Good)

        class Category extends SlicedSavable {
            constructor(...params){
                super(...params)
                this.goods = this.goods instanceof Array ? this.goods : (this.goods ? [this.goods] : []) 
            }

            static get relations(){
                return {
                    goods: "categories",
                }
            }
        }
        SlicedSavable.addClass(Category)

        class Order extends SlicedSavable {
            constructor(...params){
                super(...params)
                this.orderGoods = this.orderGoods instanceof Array ? this.orderGoods : (this.orderGoods ? [this.orderGoods] : []) 
            }

            get total(){
                return (async() => (await Promise.all(this.orderGoods)).reduce((a,b) => (a.total || a) + b.total, 0))()
            }

            static get relations(){
                return {
                    user: "orders",
                    orderGoods: "order"
                }
            }
        }
        SlicedSavable.addClass(Order)

        class OrderGood extends SlicedSavable {
            constructor(...params){
                super(...params)
            }

            get total(){
                return this.price*this.count
            }

            static get relations(){
                return {
                    good: "orderGoods",
                    order: "orderGoods"
                }
            }
        }
        SlicedSavable.addClass(OrderGood)

        const thisUser = await Savable.m.User.findOne({_id: ObjectID(id)})

        return {
            SlicedSavable, User, Good, Category, Order, OrderGood
        }
    }

    return {
        Savable, 
        slice,
        getModels
    }
}