猫鼬复杂的聚合管道问题

Question

我正在尝试完成数据聚合管道，但在将数据转换为正确格式时遇到了问题。我什至不确定这是否可以在一条管道中完成。

原始数据是这样的：

[
  {
    answers: {
      'question1': 'a',
      'question2': 'c',
      'question3': ['a','b'],
      'question4': 1
    },
    createdAt: 2022-03-04T07:30:40.517Z,
  },
  {
    answers: {
      'question1': 'b',
      'question2': 'c',
      'question3': ['a','c']
      'question4': 2
    },
    createdAt: 2022-03-04T07:30:40.518Z,
  }
]

到目前为止我已经有了我的管道：

{ $project: { 
    "answers": { $objectToArray: "$answers" },
    "date": { $dateToString: { format: "%Y-%m-%d", date: "$createdAt" }}
}},
{ $unwind: "$answers" },
{ $unwind: "$answers.v" },
{
  $group: {
     _id: { answers : "$answers", date: "$date"},
     c: { $sum: 1 }}
 },

现在数据如下所示：

{
    _id: {
      answers: { k: 'q3', v: 'b' },
      date: '2022-03-04'
    },
    count: 1
  },
  {
    _id: {
      answers: { k: 'q3', v: 'a' },
      date: '2022-03-04'
    },
    count: 2
  },
  {
    _id: {
      answers: { k: 'q4', v: 1 },
      date: '2022-03-04'
    },
    count: 1
  },
  {
    _id: {
      answers: { k: 'q1', v: 'b' },
      date: '2022-03-04'
    },
    count: 1
  },
  {
    _id: {
      answers: { k: 'q4', v: 2 },
      date: '2022-03-04'
    },
    count: 1
  },
  {
    _id: {
      answers: { k: 'q2', v: 'c' },
      date: '2022-03-04'
    },
    count: 2
  },
  {
    _id: {
      answers: { k: 'q3', v: 'c' },
      date: '2022-03-04'
    },
    count: 1
  },
  {
    _id: {
      answers: { k: 'q1', v: 'a' },
      date: '2022-03-04'
    },
    count: 1
  }

我想得到如下所示的结果：

{
    'dates': [
        {
            'date': '2022-03-04',
            'q1': { 'a': 1, 'b': 1 }
            'q2': { 'c': 2 },
            'q3': { 'a': 2, 'b': 1, 'c': 1 },
            'q4': { '1': 1, '2': 1 }
        }
    ]
    'totals': { // this would be the totals across all the dates
        'q1': { 'a': 1, 'b': 1 }
        'q2': { 'c': 2 },
        'q3': { 'a': 2, 'b': 1, 'c': 1 },
        'q4': { '1': 1, '2': 1 }
    }
}

任何帮助将不胜感激，即使我无法在 1 个查询中同时获得总数和细分。

这里是 mongoplaygroud I've been working on

Answer 1

没那么简单。您必须使用的一个重要阶段是 $facet 以获得 totals 和 dates

也许 $setWindowFields 聚合管道可以更简单一些，但这是一个快速的猜测。

db.collection.aggregate([
  {
    $project: {
      _id: 0,
      answers: { $objectToArray: "$answers" },
      date: { $dateToString: { format: "%Y-%m-%d", date: "$createdAt" } }
    }
  },
  { $unwind: "$answers" },
  { $unwind: "$answers.v" },
  {
    $group: {
      _id: {
        answer: "$answers.v",
        question: "$answers.k",
        date: "$date"
      },
      count: { $sum: 1 }
    }
  },
  {
    $facet: {
      dates: [
        {
          $group: {
            _id: { question: "$_id.question", date: "$_id.date" },
            count: {
              $push: {
                k: { $toString: "$_id.answer" },
                v: "$count"
              }
            }
          }
        },
        {
          $group: {
            _id: "$_id.date",
            count: {
              $push: {
                k: "$_id.question",
                v: { $arrayToObject: "$count" }
              }
            }
          }
        },
        {
          $replaceWith: {
            $mergeObjects: [
              { date: "$_id" },
              { $arrayToObject: "$count" }
            ]
          }
        }
      ],
      totals: [
        {
          $group: {
            _id: { answer: "$_id.answer", question: "$_id.question" },
            v: { $push: "$count" }
          }
        },
        {
          $group: {
            _id: "$_id.question",
            count: {
              $push: {
                k: { $toString: "$_id.answer" },
                v: { $sum: "$v" }
              }
            }
          }
        },
        {
          $project: {
            _id: 0,
            k: "$_id",
            v: { $arrayToObject: "$count" }
          }
        }
      ]
    }
  },
  { $set: { totals: { $arrayToObject: "$totals" } } }
])

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