server/app/service/shop/goodsRate.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 GoodsRateService extends CrudService {
  constructor(ctx) {
    super(ctx, 'goodsrate');
    this.model = this.ctx.model.Shop.GoodsRate;
  }
  /**
   * @param {Object} body 添加内容
   * @param {Object} data 添加后的结果
   */
  async afterCreate(body, data) {
    const { shop } = data;
    if (shop) await this.computedShopRate(shop);
    return data;
  }

  async computedShopRate(shop) {
    const list = await this.model.find({ shop });
    const gsList = list.map(i => i.goods_score);
    const ssList = list.map(i => i.shop_score);
    const tsList = list.map(i => i.transport_score);
    const goods_score = this.dealScore(gsList);
    const send_score = this.dealScore(ssList);
    const service_score = this.dealScore(tsList);
    await this.ctx.model.Shop.Shop.updateOne({ _id: shop }, { goods_score, send_score, service_score });
  }
  /**
   * 计算评分
   ** 该店铺所有评价的中位数以上是好评,中位数以下是差评
   ** 5分是满分,一个差评抵10个好评,一个差评 -0.01 分
   * @param {Array} arr 分数列表
   */
  dealScore(arr) {
    let score = 5;
    arr = arr.sort((a, b) => b - a);
    const length = arr.length;
    let mid,
      midIndex;
    const gl = [];
    let wl = [];
    if (length % 2 !== 0) {
      midIndex = this.ctx.plus(Math.floor(length / 2), 1);
      mid = arr[midIndex];
    } else {
      midIndex = this.ctx.divide(length, 2);
      mid = this.ctx.divide(this.ctx.plus(arr[midIndex], arr[midIndex + 1]), 2);
    }
    for (const i of arr) {
      if (i >= mid) gl.push(i);
      else wl.push(i);
    }
    const offset = _.floor(this.ctx.divide(gl.length, 10));
    wl = wl.splice(1, offset);
    score = this.ctx.minus(score, this.ctx.multiply(wl.length, 0.01));
    return score;
  }
}

module.exports = GoodsRateService;