如何用 mongoDB 中的值 0 填充缺失的文档？

Question

我有一个 collection 存储特定日期分配的水的地方。现在，在设备未运行的几天里，数据未存储在数据库中，我不会在 collection 中获取数据。例如，我正在查询过去 7 天分配的水，而设备只运行了两天，结果如下：

[{ 
    "uID" : "12345678", 
    "midNightTimeStamp" : NumberInt(1645381800), 
    "waterDispensed" : NumberInt(53)
},
{ 
    "uID" : "12345678", 
    "midNightTimeStamp" : NumberInt(1645641000), 
    "waterDispensed" : NumberInt(30)
}]

转换以上两个时间戳得到 2 月 21 日星期一和 2 月 24 日星期四的数据。现在，如果我运行查询 2 月 21 日至 2 月 27 日是这样的，

db.getCollection("analytics").find({ uID: "12345678", midNightTimeStamp: {"$in": [1645381800, 1645468200, 1645554600, 1645641000, 1645727400, 1645813800, 1645900200]}})

这 returns 我上面的两个文档，如何为提供的 midNightTimeStamp 填充缺失值以获取不存在的文档列表：

[{ 
    "uID" : "12345678", 
    "midNightTimeStamp" : 1645381800, 
    "waterDispensed" : 53
},
{ 
    "uID" : "12345678", 
    "midNightTimeStamp" : 1645468200, 
    "waterDispensed" : 0
},
{ 
    "uID" : "12345678", 
    "midNightTimeStamp" : 1645554600, 
    "waterDispensed" : 0
},
{ 
    "uID" : "12345678", 
    "midNightTimeStamp" : 1645641000, 
    "waterDispensed" : 30
},
{ 
    "uID" : "12345678", 
    "midNightTimeStamp" : 1645727400, 
    "waterDispensed" : 0
},
{ 
    "uID" : "12345678", 
    "midNightTimeStamp" : 1645813800, 
    "waterDispensed" : 0
},
{
    "uID" : "12345678", 
    "midNightTimeStamp" : 1645900200, 
    "waterDispensed" : 0
}

Answer 1

也许是这样的：

db.collection.aggregate([
{
 $group: {
   _id: null,
   ar: {
    $push: "$$ROOT"
   },
   mind: {
    "$min": "$midNightTimeStamp"
   },
   maxd: {
    "$max": "$midNightTimeStamp"
   }
  }
 },
 {
  $project: {
  ar: {
    $map: {
      input: {
        $range: [
          "$mind",
          {
            "$sum": [
              "$maxd",
              86400
            ]
          },
          86400
        ]
      },
      as: "dateInRange",
      in: {
        $let: {
          vars: {
            dateIndex: {
              "$indexOfArray": [
                "$ar.midNightTimeStamp",
                "$$dateInRange"
              ]
            }
          },
          in: {
            $cond: {
              if: {
                $ne: [
                  "$$dateIndex",
                  -1
                ]
              },
              then: {
                $arrayElemAt: [
                  "$ar",
                  "$$dateIndex"
                ]
              },
              else: {
                midNightTimeStamp: "$$dateInRange",
                "waterDispensed": NumberInt(0)
              }
            }
          }
        }
       }
      }
     }
    }
  },
  {
   $unwind: "$ar"
  },
  {
   $project: {
    _id: 0,
    "waterDispensed": "$ar.waterDispensed",
    midNightTimeStamp: "$ar.midNightTimeStamp",
    "Date": {
      $toDate: {
         "$multiply": [
         "$ar.midNightTimeStamp",
         1000
       ]
      }
    }
   }
  }
])

解释：

$group 文档以查找时间戳的最大值和最小值，并 $push 名为“ar”的临时数组中的所有元素
$project 数组 $mapping 生成的日期范围在最大值和最小值之间，步长为 1x (86400)，用 waterDispanced:0
$展开数组$ar
$project 只有我们在最终输出中需要的字段。

playground

Answer 2

这与其他答案略有不同，只需抓住所需的 "uID" 即可。 MQL 中的注释解释了该过程。

db.collection.aggregate([
  { // The uID we want
    "$match": { "uID": "12345678" }
  },
  { // grab all the uID docs as "water"
    // keep uID
    "$group": {
      "_id": null,
      "water": { "$push": "$$CURRENT" },
      "uID": { "$first": "$uID" }
    }
  },
  { // create outArray
    "$set": {
      "outArray": {
        // by mapping time vals
        "$map": {
          "input": {
            "$range": [ NumberInt(1645381800), NumberInt(1645900200), 86400 ]
          },
          "in": {
            "$cond": [
              { // already have doc?
                "$in": [ "$$this", "$water.midNightTimeStamp" ]
              },
              { // yes!  Get it!
                "$arrayElemAt": [
                  "$water",
                  { "$indexOfArray": [ "$water.midNightTimeStamp", "$$this" ] }
                ]
              },
              { // no, create it
                "uID": "$uID",
                "midNightTimeStamp": "$$this",
                "waterDispensed": 0
              }
            ]
          }
        }
      }
    }
  },
  { // only need outArray now
    "$project": {
      "_id": 0,
      "outArray": 1
    }
  },
  { // create docs
    "$unwind": "$outArray"
  },
  { // hoist them
    "$replaceWith": "$outArray"
  },
  { // don't need _id
    "$unset": "_id"
  }
])

在 mongoplayground.net 上试用。

如何用 mongoDB 中的值 0 填充缺失的文档？

How to fill missing documents with values 0 in mongoDB?

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studio3t