server/app/service/util/trade.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 TradeService extends CrudService {
  constructor(ctx) {
    super(ctx, 'trade');
    this.redis = this.app.redis;
    this.redisKey = this.app.config.redisKey;
    this.redisTimeout = this.app.config.redisTimeout;
    this.shopModel = this.ctx.model.Shop.Shop;
    this.goodsModel = this.ctx.model.Shop.Goods;
    this.goodsSpecModel = this.ctx.model.Shop.GoodsSpec;
  }
  /**
   * 检测是否可以购买该物品
   * @param {Object} param 查询条件
   * @param param.shop 商店id
   * @param param.goods 商品id
   * @param param.goodsSpec 商品规格id
   * @param param.num 购买数量
   * @param makeCache 生成缓存
   */
  async checkCanBuy({ shop, goods, goodsSpec, num }, makeCache = true) {
    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');
    assert(num, '缺少购买数量');
    const result = { result: true };
    // 1.检查商店是否正常运行
    const shopData = await this.shopModel.findById(shop);
    if (!shopData) {
      result.msg = '未找到店铺';
      result.result = false;
      return result;
    }
    if (shopData.status !== '1') {
      result.msg = '店铺不处于营业状态';
      result.result = false;
      return result;
    }
    // 2.检查商品是否可以购买
    const goodsData = await this.goodsModel.findById(goods);
    if (!goodsData) {
      result.msg = '未找到商品';
      result.result = false;
      return result;
    }
    if (goodsData.status === '0') {
      result.msg = '该商品已下架';
      result.result = false;
      return result;
    }
    // 3.检验该规格是否可以购买
    const goodsSpecData = await this.goodsSpecModel.findById(goodsSpec);
    if (!goodsSpecData) {
      result.msg = '未找到商品的指定规格';
      result.result = false;
      return result;
    }
    if (goodsSpecData.status !== '0') {
      result.msg = '该规格的商品已下架';
      result.result = false;
      return result;
    }
    if (goodsSpecData.num < num) {
      result.msg = '库存量不足';
      result.result = false;
      return result;
    }
    if (makeCache) {
      const str = this.createNonceStr();
      const key = `${this.redisKey.orderKeyPrefix}${str}`;
      const value = JSON.stringify({ shop, goods, goodsSpec, num });
      await this.redis.set(key, value, 'EX', this.redisTimeout);
      result.key = str;
    }

    return result;
  }
  // 随机字符串产生函数
  createNonceStr() {
    return Math.random().toString(36).substr(2, 15);
  }
}

module.exports = TradeService;