小编Rya*_*n M的帖子

我需要通过 mongodb 聚合管道内的 mallId 对投票内的对象进行分组。多年来一直在寻找答案，但我对 mongodb 不太熟悉，所以我有点迷茫。谁能帮我吗？

     [
      {
        "_id": "Specialty Retailer",
        "votes": [
          {
            "mallId": "59ddea3718a03a4e81f289f5",
            "count": 13
          },
          {
            "mallId": "59ddea3718a03a4e81f289f5",
            "count": 270
          },
          {
            "mallId": "59ddea3718a03a4e81f289f5",
            "count": 13
          },
          {
            "mallId": "59ddea3718a03a4e81f289f5",
            "count": 2
          },
          {
            "mallId": "59ddea3718a03a4e81f289f5",
            "count": 15
          },
          {
            "mallId": "59ddea3718a03a4e81f289f5",
            "count": 2
          }
     ]
   }
]