Python 按内部数组的特定元素分组

我正试图通过一次查询获得以下结果：

获取pub.type为deb、pub.name为Mzn的所有结果，并按pub.name对其进行分组，其中pub.type为cred

以下是示例数据：

[
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "Mzn"
      },
      {
        "type": "cred",
        "name": "Alf"
      }
    ]
  },
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "Mzn"
      },
      {
        "type": "cred",
        "name": "Alf"
      }
    ]
  },
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "Mzn"
      },
      {
        "type": "cred",
        "name": "All"
      }
    ]
  },
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "Mzn"
      },
      {
        "type": "cred",
        "name": "All"
      }
    ]
  },
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "Mzn"
      },
      {
        "type": "cred",
        "name": "All"
      }
    ]
  },
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "Mzn"
      },
      {
        "type": "cred",
        "name": "Hab"
      }
    ]
  },
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "Hab"
      },
      {
        "type": "cred",
        "name": "Alf"
      }
    ]
  },
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "Hab"
      },
      {
        "type": "cred",
        "name": "Alf"
      }
    ]
  },
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "All"
      },
      {
        "type": "cred",
        "name": "Alf"
      }
    ]
  },
  {
    "addr": "address1",
    "book": "book1",
    "pub": [
      {
        "type": "deb",
        "name": "Mzn"
      },
      {
        "type": "cred",
        "name": "Hab"
      }
    ]
  }
]

到目前为止，我已经回答了下面的问题。第一部分在

$match

块内工作正常，第二部分则不正常。它是按数组对数据进行分组，但我希望它按数组对象的元素对数据进行分组，在数组对象中它应该满足特定条件（我前面已经写过）

我曾尝试使用

$unwind

，但它只是将其拆分为数组中每个元素的对象

这是上述查询生成的结果：

这就是我需要的结果：

---

非常感谢您的帮助。

下面的内容似乎是获得答案的一种迂回方式，但这对我很有用

解卷

pub1

可能会在大型数据集中出现问题

db.getCollection('books').aggregate(  [ 
   { 
      "$match":{ 
         "pub":{ 
            $elemMatch:{ 
               "type":"deb",
               "name":"Mzn"
            }
         }
      }
   },
   { 
      "$project":{ 
         "_id":"$_id",
         "addr":"$addr",
         "book":"$book",
         "pub":"$pub",
         "pub1":"$pub"
      }
   },
   { 
      "$unwind":'$pub1'
   },
   { 
      "$match":{ 
         "pub1.type":"cred"
      }
   },
   { 
      "$group":{ 
         "_id":{ 
            "name":"$pub1.name"
         },
         "object":{ 
            "$push":{ 
               "_id":"$$ROOT._id",
               "addr":"$$ROOT.addr",
               "book":"$$ROOT.book",
               "pub":"$$ROOT.pub"
            }
         }
      }
   }
])

“所需结果”中的json数据是您需要的最终输出，还是“按pub.name将它们分组，其中pub.type是cred”？

db.getCollection('books').aggregate(  [ 
   { 
      "$match":{ 
         "pub":{ 
            $elemMatch:{ 
               "type":"deb",
               "name":"Mzn"
            }
         }
      }
   },
   { 
      "$project":{ 
         "_id":"$_id",
         "addr":"$addr",
         "book":"$book",
         "pub":"$pub",
         "pub1":"$pub"
      }
   },
   { 
      "$unwind":'$pub1'
   },
   { 
      "$match":{ 
         "pub1.type":"cred"
      }
   },
   { 
      "$group":{ 
         "_id":{ 
            "name":"$pub1.name"
         },
         "object":{ 
            "$push":{ 
               "_id":"$$ROOT._id",
               "addr":"$$ROOT.addr",
               "book":"$$ROOT.book",
               "pub":"$$ROOT.pub"
            }
         }
      }
   }
])