Question

我的文件如下。

{
    "name" : "MadhuA"+i,
    "lastname" : "MohanB"+i,
    "created" : new Date(),
    "Address" : [
        {
            "Home Address" : "St:123, Abcd road, cityA, stateB, Pin code123",
            "Work Address" : "St:134, xyz road, cityV, stateX, pin code456",
            "Billing Address" : "St:156, pppp road, cityZ, stateNm ,Pincode154"
        }
    ],
    "tariff" : [
        {
            "Service" : "Broadband",
            "Recurring" : "Monthly",
            "Fee" : 100
        }
    ],
    "charges" : [ {
            "charge_details" : [
                {
                    "start_date" : "01-JAN-2016",
                    "end_date" : "01-FEB-2016",
                    "charge_amount" : Math.floor(Math.random()*400),
                    "Status" : "Outstanding",
                    "Service" : "Broadband",
                    "charge_type" : "monthly"
                },
                {
                    "start_date" : "01-JAN-2016",
                    "end_date" : "01-FEB-2016",
                    "charge_amount" : Math.floor(Math.random()*400),
                    "Status" : "Outstanding",
                    "Service" : "VoIP",
                    "charge_type" : "monthly"
                }
            ] }
        ]
}

我希望使用费用字段中的所有charge_amounts填充总金额。只要在文档中添加了charge_amount，就应该相应地更改total_amount。如果我们有这样的功能，请告诉我。

＆lt; 3

Answer 1

如果我理解正确，您尝试添加属性totalAmount，以便：

包含charge_amount值
文档更改时动态更改

如果是这种情况，最好的解决方案是使用带有视图的Mongo 3.4，编写如下内容：

db.createView("totalAmount", "collection", [
  { 
   $addFields: {
       totalAmount:  "$charges.charge_details.charge_amount" 
     }
  },
  { 
   $addFields: {
       totalAmount:  { $arrayElemAt: ["$totalAmount",0] } 
     }
  },
])

这里我假设您的收藏被称为＆＃34;收集＆＃34; 现在，您可以查询新视图，您将看到totalAmount：

db.totalAmount.find().pretty

所示：

{
    "_id" : ObjectId("5856c41fbd0535e2fb8fb2ff"),
    "name" : "MadhuA",
    "lastname" : "MohanB",
    "created" : ISODate("2016-12-18T17:15:11.797Z"),
    "Address" : [
        {
            "Home Address" : "St:123, Abcd road, cityA, stateB, Pin code123",
            "Work Address" : "St:134, xyz road, cityV, stateX, pin code456",
            "Billing Address" : "St:156, pppp road, cityZ, stateNm ,Pincode154"
        }
    ],
    "tariff" : [
        {
            "Service" : "Broadband",
            "Recurring" : "Monthly",
            "Fee" : 100
        }
    ],
    "charges" : [
        {
            "charge_details" : [
                {
                    "start_date" : "01-JAN-2016",
                    "end_date" : "01-FEB-2016",
                    "charge_amount" : 37,
                    "Status" : "Outstanding",
                    "Service" : "Broadband",
                    "charge_type" : "monthly"
                },
                {
                    "start_date" : "01-JAN-2016",
                    "end_date" : "01-FEB-2016",
                    "charge_amount" : 398,
                    "Status" : "Outstanding",
                    "Service" : "VoIP",
                    "charge_type" : "monthly"
                }
            ]
        }
    ],
    "totalAmount" : [
        37,
        398
    ]
}

此外，如果您将新文档添加到＆＃34; collection＆＃34;或修改任何文档视图（特别是totalAmount）将相应更改。

Answer 2

出现此错误：

> db.totalAmount.find({"name" : "MadhuA4097899"}).pretty()
Error: error: {
    "ok" : 0,
    "errmsg" : "$arrayElemAt's first argument must be an array, but is int",
    "code" : 28689,
    "codeName" : "Location28689"
}

MongoDB中的计算字段

2 个答案: