server/app/service/trade/cart.js

'use strict';
const { CrudService } = require('naf-framework-mongoose-free/lib/service');
const { BusinessError, ErrorCode } = require('naf-core').Error;
const _ = require('lodash');
const assert = require('assert');

//
class CartService extends CrudService {
  constructor(ctx) {
    super(ctx, 'cart');
    this.model = this.ctx.model.Trade.Cart;
    this.goodsSpecModel = this.ctx.model.Shop.GoodsSpec;
  }

  /**
   * 返回购物车需要的数据格式
   * @param {Object} query 查询条件
   * @param query.customer 顾客id
   * @return {Array}
   */
  async selfCart({ customer }) {
    assert(customer, '缺少顾客信息');
    const { populate } = this.getRefMods();
    let list = await this.model.find({ customer }).populate(populate);
    list = JSON.parse(JSON.stringify(list));
    list = list.map(i => {
      const obj = {};
      obj.cart = _.get(i, '_id');
      obj.shop_name = _.get(i.shop, 'name');
      obj.shop = _.get(i.shop, '_id');
      obj.goods = this.setCartGoodsData(i.goods, i.goodsSpec);
      return obj;
    });
    list = _.groupBy(list, 'shop');
    const arr = [];
    for (const key in list) {
      const shopGroup = list[key];
      const goods = shopGroup.reduce((p, n) => {
        p.push(n.goods);
        return p;
      }, []);
      const shop = _.omit(_.head(shopGroup), [ 'goods' ]);
      arr.push({ ...shop, goods });
    }
    return arr;
  }

  /**
   * 重组购物车商品
   * @param {Object} goods 商品
   * @param {Object} goodsSpec 商品规格
   */
  setCartGoodsData(goods, goodsSpec) {
    const obj = {};
    obj.goods_id = _.get(goods, '_id');
    obj.goods_name = _.get(goods, 'name');
    obj.goodsSpec_id = _.get(goodsSpec, '_id');
    obj.goodsSpec_name = _.get(goodsSpec, 'name');
    obj.money = _.get(goodsSpec, 'sell_money');
    obj.num = _.get(goodsSpec, 'num');
    obj.file = _.get(goods, 'file');
    return obj;
  }

  /**
   * 创建购物车信息,若找到该店的该商品规格.进行库存校验
   * 数量进行合并;
   * 反之创建
   * @param {Object} body 请求参数
   * @param body.num 数量
   */
  async create({ num, ...body }) {
    const { customer, shop, goods, goodsSpec } = body;
    assert(customer, '缺少顾客信息');
    assert(shop, '缺少店铺信息');
    assert(goods, '缺少商品信息');
    assert(goodsSpec, '缺少商品规格信息');
    const data = await this.model.findOne(body);
    if (data) {
      const buyNum = parseInt(data.num) + parseInt(num);
      const { enough } = await this.checkGoodsNum({ goodsSpecId: goodsSpec, num: buyNum });
      if (!enough) throw new BusinessError(ErrorCode.SERVICE_FAULT, '库存不足,无法添加至购物车');
      data.num = buyNum;
      await data.save();
    } else {
      const { enough } = await this.checkGoodsNum({ goodsSpecId: goodsSpec, num });
      if (!enough) throw new BusinessError(ErrorCode.SERVICE_FAULT, '库存不足,无法添加至购物车');
      await this.model.create({ num, ...body });
    }
  }

  /**
   * 检查商品规格的库存
   * @param {String} goodsSpecId 商品规格id
   * @param {Number} num 需要的库存数量
   * @return {Boolean} true:库存满足购物车条件;false:库存不满足条件
   */
  async checkGoodsNum({ goodsSpecId, num }) {
    const goodsSpec = await this.goodsSpecModel.findById(goodsSpecId);
    if (!goodsSpec) throw new BusinessError(ErrorCode.DATA_NOT_EXIST, '未找到商品的规格数据');
    const { num: gsnum = 0 } = goodsSpec;
    return { enough: gsnum >= num, total: gsnum };
  }
}

module.exports = CartService;