如何将字段与MongoDB中的阵列进行比较

Question

我有以下文件。我想检索所有地址的文档。

    [  
     {
    "name": "star1",
    "active": 1,
    "address": [
      {
        "id": 1,
        "city": "newyork"
      },
      {
        "id": 2,
        "city": "sydney"
      }
    ]  
   },  
  {
    "name": "star2",
    "active": 2,
    "address": [
      {
        "id": 1,
        "city": "newyork"
      },
      {
        "id": 2,
        "city": "london"
      }
    ]  
}
]

我已经写了以下查询，它部分有效，但是它没有返回完整的文档。我不能使用Undind。我们有任何解决方案而无需使用“ Undind”。是否可以仅通过$匹配解决问题

db.collection.aggregate([
  {
    $unwind: "$address"
  },
  {
    $match: {
      $expr: {
        $eq: [
          "$active",
          "$address.id"
        ]
      },
      "address.city": "newyork"
    }
  }
])

Answer 1

如果您需要匹配整个文档，该文档包含至少一个条目{address.id == active and adverty.city == newyork}以下是一个选项：

db.collection.aggregate([
 {
   $match: {
    $expr: {
      "$in": [
        {
          id: "$active",
          city: "newyork"
        },
        "$address"
       ]
     }
   }
 }
])

解释：

仅匹配具有至少一个在地址数组中的对象的文档== $ active and city ==“ newyork”

playground

> ，更正确的选项如下：

db.collection.aggregate([
{
 $match: {
  $expr: {
    $or: [
      {
        "$in": [
          {
            id: "$active",
            city: "newyork"
          },
          "$address"
        ]
      },
      {
        "$in": [
          {
            city: "newyork",
            id: "$active"
          },
          "$address"
        ]
      }
    ]
   }
  }
 }
])

解释：

仅匹配文档至少在数组中具有{id == $ active and active and city ==“ newyork”}或{city ==“ newyork”和id == $ active }

Playground 2

Answer 2

也许是这样的：

db.collection.aggregate([
{
"$addFields": {
  "address": {
    "$filter": {
      "input": "$address",
      "as": "a",
      "cond": {
        $and: [
          {
            $eq: [
              "$a.id",
              "$active"
            ]
          },
          {
            $eq: [
              "$a.city",
              "newyork"
            ]
          }
        ]
      }
    }
  }
}
},
{
 $match: {
  address: {
     $ne: []
    }
  }
}
])

解释：

1. 使用AddFields/filter仅匹配数组中的匹配文档。
2. 在未找到子图案的情况下，从数组中删除带有空地址的文档。

Playground