code: async function newest(ctx) {
    let cid = ctx.query.cid || _2.default.error(400);
    const { cache } = _2.default;
    let cacheKey = `goods_newest_${cid}`;
    let results = await cache.get(cacheKey);
    if (!results) {
      // $Flow find
      let mResults = await _Goods2.default.find({ activated: true, cats: cid }).sort('-createdAt').limit(10);
      // $Flow
      results = mResults.map(goods => goods.data().omit('desc', 'pics', 'skus', 'cat'));
      cache.set(cacheKey, results, 600 * 1000);
    }
    ctx.body = results;
  }
docs: 获取某个分类下的10个最新产品
  @param ctx
  @returns {Promise.<void>}