$ group由MongoDb aggreagte中的每个唯一字符串组成

debugcn 发表于 Dev

维蒙德

我在MongoDB中有大量的事件文档，希望将其分组createdAt，并获得title当天创建的事件的唯一值。

活动文档如下：

{
   "createdAt": 2020-02-03T00:00:00.000Z,
   "title": "Book meeting"
}

到目前为止，我得到了输出：

[{
        "titles": [
          "Book meeting",
          "Book meeting",
          "Personal meeting",
          "Personal meeting",
          "Book meeting",
          "Book meeting",
          "Book meeting",
          "Book meeting",
          "Training",
          "Book meeting",
          "Book meeting",
          "Book meeting",
          "Book meeting",
          "Book meeting",
          "Book meeting",
          "Book meeting",
          "Digital meeting",
          "Support"
        ],
        "date": "2020-02-03T00:00:00.000Z"
}, ...events ],

但我希望它是：

{
        "Book meeting": 10,
        "Digital meeting": 7,
        ...for all titles
        "date": "2020-02-03T00:00:00.000Z"
},

到目前为止，这是我正在做的事情：

    Events.aggregate().group({
        _id: {
          createdAt: "$createdAt",
          title: "$title"
        }
      })
      .group({
        _id: {
          year: { $year: "$_id.createdAt" },
          month: { $month: "$_id.createdAt" },
          day: { $dayOfMonth: "$_id.createdAt" }
        },
        titles: { $push: "$_id.title" }
      })
      .project({
        _id: 0,
        date: {
          $dateToString: {
            date: {
              $dateFromParts: {
                year: "$_id.year",
                month: "$_id.month",
                day: "$_id.day"
              }
            }
          }
        },
        titles: 1,
      })

瓦利洪

尝试这个：

Events.aggregate([
  {
    $group: {
      _id: {
        title: "$title",
        date: {
          $dateToString: {
            date: "$createdAt",
            format: "%Y-%m-%d"
          }
        }
      },
      count: {
        $sum: 1
      }
    }
  },
  {
    $group: {
      _id: "$_id.date",
      titles: {
        $push: {
          k: "$_id.title",
          v: "$count"
        }
      }
    }
  },
  {
    $addFields: {
      titles: {
        $mergeObjects: [
          {
            "date": {
              $concat: [
                "$_id",
                "T00:00:00.000Z"
              ]
            }
          },
          {
            $arrayToObject: "$titles"
          }
        ]
      }
    }
  },
  {
    $replaceWith: "$titles"
  }
]).exec();

蒙哥运动场

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