MongoDB Compass：如何过滤 MongoDB 文档中嵌入的数组对象

Question

我想根据 importkeyid 和 MissingPersonIds.PhotoId 数组字段过滤文档。 MissingPersonIds.PhotoId 上的过滤器应该像 'sql - like' 运算符一样工作。

架构：

[{
  "_id": {
    "$oid": "61ada7da9a30fd8471869bbc"
  },
  "ImportKeyId": 5843,
  "Name" : "AV"
  "MissingPersonIds": [
    {
      "PhotoId": "2 - Copy.jpg",
      "Description": "Account ID not found"
    },
    {
      "PhotoId": "2 - Copy - Copy.jpg",
      "Description": "Account ID not found"
    },
    {
      "PhotoId": "2 - Copy - Copy (2).jpg",
      "Description": "Account ID not found"
    },
    {
      "PhotoId": "202020 - Copy (2).jpg",
      "Description": "Account ID not found"
    },
    {
      "PhotoId": "202020 - Copy - Copy.jpg",
      "Description": "Account ID not found"
    },
    {
      "PhotoId": "202020 - Copy - Copy (2).jpg",
      "Description": "Account ID not found"
    }
  ]
},
{
  "_id": {
    "$oid": "619cd7d2181999c9a4da790a"
  },
  "ImportKeyId": 5753,
  "Name" : 'av1'
  "MissingPersonIds": [
    {
      "PhotoId": "94578.jpg",
      "Description": "Photo id is not found"
    },
    {
      "PhotoId": "371426759.jpg",
      "Description": "Photo id is not found"
    }
  ]
}
.
.
.
]

基于以下条件：

过滤器：{ "ImportKeyId" : 5843 }

投影：{ MissingPersonIds : { $slice:[0,5] }, "MissingPersonIds": { $elemMatch: { PhotoId : { $regex: /202020 /i } } } }

我期待低于输出但 $elemMatch returns 只有一个匹配的记录

[{
  "_id": {
    "$oid": "61ada7da9a30fd8471869bbc"
  },
  "ImportKeyId": 5843,
  "Name" : "AV"
  "MissingPersonIds": [  
    {
      "PhotoId": "202020 - Copy (2).jpg",
      "Description": "Account ID not found"
    },
    {
      "PhotoId": "202020 - Copy - Copy.jpg",
      "Description": "Account ID not found"
    }
  ]
}]

我应该用什么代替 $elemMatch？

Answer 1

可能是 this

db.collection.aggregate([
  {
    "$match": {
      "ImportKeyId": 5843
   }
  },
 {
"$project": {
  "_id": 1,
  "ImportKeyId": 1,
  MissingPersonIds: {
    $filter: {
      input: "$MissingPersonIds",
      as: "item",
      cond: {
        $gt: [
          {
            $indexOfCP: [
              {
                $toLower: "$$item.PhotoId"
              },
              "202020 "
            ]
          },
          -1
        ]
      }
    }
  }
  }
  }
 ])

输出：

[
  {
    "_id": ObjectId("61ada7da9a30fd8471869bbc")
    "ImportKeyId": 5843,
    "MissingPersonIds": [
  {
    "Description": "Account ID not found",
    "PhotoId": "202020 - Copy (2).jpg"
  },
  {
    "Description": "Account ID not found",
    "PhotoId": "202020 - Copy - Copy.jpg"
  },
  {
    "Description": "Account ID not found",
    "PhotoId": "202020 - Copy - Copy (2).jpg"
  }
  ],
 
  }
]

解释：

在匹配阶段，您仅过滤具有 ImportKeyId 的文档：5843
在项目阶段，您将 _id 和 ImportKeyId 添加到新字段 MissingPersonIds 中，该字段将过滤仅包含字符串的数组中的元素，例如 SQL 中具有“%202020 %”的字符串

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