Question

我们说我有一组对象：

{
   _id : 1,
   list1 : [
      { name: 'This is my name', value: 'This is my value' },
      { name: 'name number 2', value: 'value number 2' }
   ],
   list2 : [
      { name: 'Another name', value: 'Another value' }
   ],
   deeper : {
      list3 : [
         { name: 'Another name but even deeper', value: 'Another value but deeper' }
      ]
   }
}

使用聚合管道如何返回单个名称/值对象列表？结果应该是：

{
   _id : 1,
   combinedList : [
      { name: 'This is my name', value: 'This is my value' },
      { name: 'name number 2', value: 'value number 2' },
      { name: 'Another name', value: 'Another value' },
      { name: 'Another name but even deeper', value: 'Another value but deeper' }
   ]
}

第2部分：

现在，如何将整个集合中的深层嵌套对象展平为单个响应？例如：

{
   "_id" : 0,
   list1 : [
      { name: 'This is my name', value: 'This is my value' },
      { name: 'name number 2', value: 'value number 2' }
   ],
   list2 : [
      { name: 'Another name', value: 'Another value' }
   ]
},
{
   "_id" : 1,
   list1 : [
      { name: 'This is my name', value: 'This is my value' },
      { name: 'name number 2', value: 'value number 2' }
   ],
   deeper : {
      list2 : [
         { name: 'Another name but even deeper', value: 'Another value but deeper' }
      ]
   }
}

结果应该与上面的文档相同（combinedList）。

Answer 1

您可以使用aggregate和setUnion

db.coll.aggregate([
    {
        $match:{_id:1}  
    },
     { 
         $project: {_id: 0 ,
                    combinedList: { $setUnion: [ "$deeper.list3","$list2", "$list1" ] }} 
     }
   ]
)

结果

{
    "result" : [ 
        {
            "combinedList" : [ 
                {
                    "name" : "Another name but even deeper",
                    "value" : "Another value but deeper"
                }, 
                {
                    "name" : "Another name",
                    "value" : "Another value"
                }, 
                {
                    "name" : "name number 2",
                    "value" : "value number 2"
                }, 
                {
                    "name" : "This is my name",
                    "value" : "This is my value"
                }
            ]
        }
    ],
    "ok" : 1
}

http://docs.mongodb.org/manual/reference/operator/aggregation/setUnion/

你必须使用2.6版本。

MongoDB聚合管道和深层嵌套对象的组合

1 个答案: