MongoDB：对象的深度嵌套数组中的聚合查找

我有两个收藏：

音频

[
       {
        "_id": "5f6b1a2e69eef14818ca03a7",
        "audioURL": "https://boyd.org",
        "state": "draft",
       }
       {
        "_id": "5f6b1e1c6297f34bc6f1fee3",
        "name": "navigate",
        "audioURL": "http://mariane.org",
        "state": "draft",
       },
       {
        "_id": "5f5b5423ba39f738d593b504",
        "audioURL": "https://storage/test123mp31599820832928.mp3",
        "state": "draft",
       }
]

经验教训：

 "lessons": [
  {
   "_id": "5f770e275cef7a611f3cf931",
   "minigameDescriptions": [
    {
     "assessmentSections": [
      {
       "mark": "step_1",
       "start": 1,
       "end": 2,
       "stepAudio": {
        "backingTrackAudioId": "5f6b1a2e69eef14818ca03a7",
        "previewTrackAudioId": "5f6b1a2e69eef14818ca03a7"
       }
      },
      {
       "mark": "step_2",
       "start": 3,
       "end": 6,
       "stepAudio": {
        "backingTrackAudioId": "5f6b1e1c6297f34bc6f1fee3",
        "previewTrackAudioId": "5f6b1e1c6297f34bc6f1fee3"
       }
      },
      {
       "mark": "step_3",
       "start": 7,
       "end": 10,
       "stepAudio": {
        "backingTrackAudioId": "5f6b1a2e69eef14818ca03a7",
        "previewTrackAudioId": "5f5b5423ba39f738d593b504"
       }
      }
     ],
     "drumStyleName": "DrumStyleHalftimeShuffle",
     "onboarding": false,
     "showHints": false,
     "minigameType": "StrummingTrainer",
    }
   ],
   "_updated_at": "2020-10-02T12:00:23.848Z",
  }
 ]
}

现在我必须将其聚合起来，因为在每个

mingameDescriptions.assessment部分

中都有属性

stepAudio

，该属性具有

previewTrackAudioId

和

backingTrackAudioId

。这些对集合“audios”的引用，我需要将它们作为对象加入其中（audio主键是

\u id

）。我尝试了以下管道（现在我只尝试查找

previewTrackAudio

）：

它“有点”起作用，我得到以下结果：

{
 "lessons": [
  {
   "_id": "5f770e275cef7a611f3cf931",
   "minigameDescriptions": [
    {
     "assessmentSections": {
      "mark": "step_2",
      "start": 3,
      "end": 6,
      "stepAudio": {
       "backingTrackAudioId": "5f6b1e1c6297f34bc6f1fee3",
       "previewTrackAudioId": "5f6b1e1c6297f34bc6f1fee3",
       "previewTrackAudio": {
        "_id": "5f6b1e1c6297f34bc6f1fee3",
        "name": "navigate",
        "audioURL": "http://mariane.org",
        "state": "draft",
       }
      }
     },
     "drumStyleName": "DrumStyleHalftimeShuffle",
     "onboarding": false,
     "showHints": false,
     "minigameType": "StrummingTrainer",
    },
    {
     "assessmentSections": {
      "mark": "step_3",
      "start": 7,
      "end": 10,
      "stepAudio": {
       "backingTrackAudioId": "5f6b1a2e69eef14818ca03a7",
       "previewTrackAudioId": "5f5b5423ba39f738d593b504",
       "previewTrackAudio": {
        "_id": "5f5b5423ba39f738d593b504",
        "audioURL": "https://storage/test123mp31599820832928.mp3",
        "state": "draft",
       }
      }
     },
     "drumStyleName": "DrumStyleHalftimeShuffle",
     "onboarding": false,
     "showHints": false,
     "minigameType": "StrummingTrainer",
    },
    {
     "assessmentSections": {
      "mark": "step_1",
      "start": 1,
      "end": 2,
      "stepAudio": {
       "backingTrackAudioId": "5f6b1a2e69eef14818ca03a7",
       "previewTrackAudioId": "5f6b1a2e69eef14818ca03a7",
       "previewTrackAudio": {
        "_id": "5f6b1a2e69eef14818ca03a7",
        "audioURL": "https://boyd.org",
        "state": "draft",
       }
      }
     },
     "drumStyleName": "DrumStyleHalftimeShuffle",
     "onboarding": false,
     "showHints": false,
     "minigameType": "StrummingTrainer",
    }
   ],
   "_updated_at": "2020-10-02T12:00:23.848Z",
  }
 ]
}

但是现在没有了一个包含3个

mingameDescriptions.assessmentSections

的数组，我有了一个包含三个对象的数组，它们包含

assessmentSections

以及

minigamescriptions

中的重复属性，这是错误的：/。我怎样才能解决这个问题

我想得到的是：

 "lessons": [
  {
   "_id": "5f770e275cef7a611f3cf931",
   "minigameDescriptions": [
    {
     "assessmentSections": [
      {
       "mark": "step_1",
       "start": 1,
       "end": 2,
       "stepAudio": {
        "backingTrackAudioId": "5f6b1a2e69eef14818ca03a7",
        "previewTrackAudioId": "5f6b1a2e69eef14818ca03a7",
        "previewTrackAudio": {
         "_id": "5f6b1a2e69eef14818ca03a7",
         "audioURL": "https://boyd.org",
         "state": "draft",
        }
       }
      },
      {
       "mark": "step_2",
       "start": 3,
       "end": 6,
       "stepAudio": {
        "backingTrackAudioId": "5f6b1e1c6297f34bc6f1fee3",
        "previewTrackAudioId": "5f6b1e1c6297f34bc6f1fee3",
        "previewTrackAudio": {
          "_id": "5f5b5423ba39f738d593b504",
          "audioURL": "https://storage/test123mp31599820832928.mp3",
          "state": "draft",
         }
       }
      },
      {
       "mark": "step_3",
       "start": 7,
       "end": 10,
       "stepAudio": {
        "backingTrackAudioId": "5f6b1a2e69eef14818ca03a7",
        "previewTrackAudioId": "5f5b5423ba39f738d593b504",
        "previewTrackAudio": {
         "_id": "5f5b5423ba39f738d593b504",
         "audioURL": "https://storage/test123mp31599820832928.mp3",
         "state": "draft",
        }
       }
      }
     ],
     "drumStyleName": "DrumStyleHalftimeShuffle",
     "onboarding": false,
     "showHints": false,
     "minigameType": "StrummingTrainer",
    }
   ],
   "_updated_at": "2020-10-02T12:00:23.848Z",
  }
 ]
}

---

你所尝试的是正确的

[
  {
    $unwind: "$minigameDescriptions"
  },
  {
    $unwind: "$minigameDescriptions.assessmentSections"
  },
  {
    $lookup: {
      from: "Audios",
      let: {
        audioId: "$minigameDescriptions.assessmentSections.stepAudio.previewTrackAudioId"
      },
      pipeline: [
        {
          $match: {
            $expr: {
              $eq: [
                "$_id",
                "$$audioId"
              ]
            }
          }
        }
      ],
      as: "minigameDescriptions.assessmentSections.stepAudio.previewTrackAudio"
    }
  },
      {
    $group: {
      _id: {
        _id: "$_id",
        /**   assId: "$minigameDescriptions.assessmentSections.mark"*/
        
      },
      assessmentSections: {
        $addToSet: "$minigameDescriptions.assessmentSections"
      },
      drumStyleName: {
        $first: "$minigameDescriptions.drumStyleName"
      },
      minigameType: {
        $first: "$minigameDescriptions.minigameType"
      }
    }
  },
  {
    $group: {
      _id: "$_id",
      minigameDescriptions: {
        $addToSet: {
          assessmentSections: "$assessmentSections",
          drumStyleName: "$drumStyleName",
          minigameType: "$minigameType"
        }
      }
    }
  }
]

工作

---

注意：这里我们做了两次退绕，所以最好执行分组操作。请注意，我在第一组中对您的文档中未出现的

assessmentId

进行了注释。但是，如果您有任何东西来识别

评估部分中的每个元素，则更好，这有助于避免变得复杂
您需要发布这两个集合。不要在查看itRight时发布不必要的字段，这会让其他人感到不舒服。我已经发布了这两个集合并删除了不必要的字段。这几乎就是我需要的，谢谢！我编辑了这篇文章以添加我需要的回复，因为在您的解决方案中，我只得到
评估部分
，而
迷你游戏描述
中的其余属性缺失。你能帮我吗？我已经更新了我的答案，我已经做了几个领域，你可以按照同样的方式，这对你有帮助吗？我会检查，稍后让你知道！
[
  {
    $unwind: "$minigameDescriptions"
  },
  {
    $unwind: "$minigameDescriptions.assessmentSections"
  },
  {
    $lookup: {
      from: "Audios",
      let: {
        audioId: "$minigameDescriptions.assessmentSections.stepAudio.previewTrackAudioId"
      },
      pipeline: [
        {
          $match: {
            $expr: {
              $eq: [
                "$_id",
                "$$audioId"
              ]
            }
          }
        }
      ],
      as: "minigameDescriptions.assessmentSections.stepAudio.previewTrackAudio"
    }
  },
      {
    $group: {
      _id: {
        _id: "$_id",
        /**   assId: "$minigameDescriptions.assessmentSections.mark"*/
        
      },
      assessmentSections: {
        $addToSet: "$minigameDescriptions.assessmentSections"
      },
      drumStyleName: {
        $first: "$minigameDescriptions.drumStyleName"
      },
      minigameType: {
        $first: "$minigameDescriptions.minigameType"
      }
    }
  },
  {
    $group: {
      _id: "$_id",
      minigameDescriptions: {
        $addToSet: {
          assessmentSections: "$assessmentSections",
          drumStyleName: "$drumStyleName",
          minigameType: "$minigameType"
        }
      }
    }
  }
]