MongoDb 创建聚合创建查询答案

【问题标题】：MongoDb Create Aggregate Create queryMongoDb 创建聚合创建查询
【发布时间】：2021-09-14 23:30:45
【问题描述】：

我有 3 个表用户，班次，临时班次，

shifts:[{_id:ObjectId(2222),name:"Morning"},{_id:ObjectId(454),name:"Night"}]
users:[{_id:ObjectId(123),name:"Albert",shift_id:ObjectId(2222)}]

temporaryShifts:[
{_id:2,userId:ObjectId(123),shiftId:ObjectId(454),type:"temporary",date:"2020-02-01"},
{_id:987,userId:ObjectId(123),shiftId:ObjectId(454),type:"temporary",date:"2020-02-03"},
{_id:945,userId:ObjectId(123),shiftId:ObjectId(454),type:"temporary",date:"2020-02-08"},
{_id:23,userId:ObjectId(123),shiftId:ObjectId(454),date:"2020-02-09"}]

我想做一个猫鼬聚合查询然后给我结果：在两个日期之间获取结果，例如：2020-02-01 2020-02-05，结果是：

[
{_id:ObjectId(123),name:"Albert",shift:[
{_id:2,shiftId:ObjectId(454),type:"temporary",date:"2020-02-01"},
{_id:2,shiftId:ObjectId(2222),type:"permanent",date:"2020-02-02"},
{_id:2,shiftId:ObjectId(454),type:"temporary",date:"2020-02-03"},
{_id:2,shiftId:ObjectId(2222),type:"permanent",date:"2020-02-04"},
{_id:2,shiftId:ObjectId(2222),type:"permanent",date:"2020-02-05"},
]}
]

在结果类型中临时表示在表中选择的日期temporaryShift文档可用，否则类型为永久

MongoPlayGround You Can edit

【问题讨论】：

标签： mongodb mongoose mongodb-query aggregate

【解决方案1】：

您可以首先使用$range 投影日期范围数组，在您的示例中，它将类似于 [2020-02-01, 2020-02-02, 2020-02-03, 2020-02-04, 2020- 02-05]，那么就可以使用数组来执行$lookup

db.users.aggregate([
  {
    $limit: 1
  },
  {
    "$addFields": {
      "startDate": ISODate("2020-02-01"),
      "endDate": ISODate("2020-02-05")
    }
  },
  {
    "$addFields": {
      "dateRange": {
        "$range": [
          0,
          {
            $add: [
              {
                $divide: [
                  {
                    $subtract: [
                      "$endDate",
                      "$startDate"
                    ]
                  },
                  86400000
                ]
              },
              1
            ]
          }
        ]
      }
    }
  },
  {
    "$addFields": {
      "dateRange": {
        $map: {
          input: "$dateRange",
          as: "increment",
          in: {
            "$add": [
              "$startDate",
              {
                "$multiply": [
                  "$$increment",
                  86400000
                ]
              }
            ]
          }
        }
      }
    }
  },
  {
    "$unwind": "$dateRange"
  },
  {
    "$project": {
      "name": 1,
      "shiftId": 1,
      "dateCursor": "$dateRange"
    }
  },
  {
    "$lookup": {
      "from": "temporaryShifts",
      "let": {
        dateCursor: "$dateCursor",
        shiftId: "$shiftId"
      },
      "pipeline": [
        {
          "$addFields": {
            "parsedDate": {
              "$dateFromString": {
                "dateString": "$date",
                "format": "%Y-%m-%d"
              }
            }
          }
        },
        {
          $match: {
            $expr: {
              $and: [
                {
                  $eq: [
                    "$$dateCursor",
                    "$parsedDate"
                  ]
                }
              ]
            }
          }
        }
      ],
      "as": "temporaryShiftsLookup"
    }
  },
  {
    "$unwind": {
      path: "$temporaryShiftsLookup",
      preserveNullAndEmptyArrays: true
    }
  },
  {
    $project: {
      shiftId: 1,
      type: {
        "$ifNull": [
          "$temporaryShiftsLookup.type",
          "permanent"
        ]
      },
      date: "$dateCursor"
    }
  }
])

这里是Mongo Playground 供您参考。

【讨论】：