Question

我有对象数组（嵌套），我想从这些嵌套对象中提取几个元素，并在数组中返回这些字段。下面是我的文档结构（从原始数据中嘲笑）

"detailLine": [
    {
        "name": "first",
        "value": {
            "lineNumber": 1,
            "subLineCode": " ",
            "detailLineCharges": {
                "allowedAmount": {
                    "amount": "11111",
                    "reasonCode": “aaaah”
                }
            }
        }
    },
    {
        "name": "first",
        "value": {
            "detailLineCharges": {
                "allowedAmount": {
                    "amount": "22222",
                    "reasonCode": “BBBB”
                }
            }
        }
    }
]

我希望看到我的结果

details: [
  {
    amount:”11111”,
    reasonCode : “aaaah”
  },
  {
    amount : “22222”,
    reasonCode : “BBBB”
  }
]

我试过

 db.collection.aggregate([
   {
     $match: {
       _id: "123456"
     }
   }, 
   {
     $project: {
       details: {
         $push {
           amount: "$detailLine.value.detailLineCharges.allowedAmount.amount",
           reasoncode: "$detailLine.value.detailLineCharges.allowedAmount.reasonCode"
         }
       }
     }
   }
])

但我收到此错误

Error: command failed: { "ok" : 0, "errmsg" : "invalid operator '$push'", "code" : 15999 } : aggregate failed :

我想使用$project，因为我使用它来提取太多其他字段，这就是为什么我没有尝试$group这个特定情况。

任何人都可以帮助如何在数组中获取这两个字段吗？

Answer 1

嗯，您需要的只是$project您的文档，并使用$map运算符“重塑”它们。

db.coll.aggregate( 
    [ 
        { "$match": { "_id": "123456" } },
        { "$project": { 
            "detailLine": { 
                "$map": { 
                    "input": "$detailLine", 
                    "as": "dline", 
                    "in": { 
                        "amount": "$$dline.value.detailLineCharges.allowedAmount.amount", 
                        "reasonCode": "$$dline.value.detailLineCharges.allowedAmount.reasonCode" 
                    } 
                } 
           } 
        }} 
    ]
)

Answer 2

使用以下管道，虽然我使用given，但它会为您提供所需的结果。当然，您可能需要调整组标识符。

|scenario | myDivision _ _ _|numerator, denominator, quotient|
|setNumerator    | @numerator  |
|setDenominator  | @denominator|
|check | quotient| @quotient   |

| myDivision | having |numerator| 12| 
| denominator|quotient|
|  3         |4.0     |
|  6         |2.0     |
|  4         |3.0     |

结果

$group

Answer 3

您忘记在$ push中添加冒号

\n\n

更改为

$project: {
   details: {
     $push {
       amount: "$detailLine.value.detailLineCharges.allowedAmount.amount",
       reasoncode: "$detailLine.value.detailLineCharges.allowedAmount.reasonCode"
     }
   }
 }

将MongoDB项目转换为数组

3 个答案: