将字符串转换为mongodb中数组中的数值和计数和_Mongodb_Mongodb Query_Aggregation Framework

将字符串转换为mongodb中数组中的数值和计数和

mongodb

将字符串转换为mongodb中数组中的数值和计数和,mongodb,mongodb-query,aggregation-framework,Mongodb,Mongodb Query,Aggregation Framework,我想用数组中的字符串类型求总金额，所以我在mongo中写这个。需要帮忙吗已尝试： db.compte.aggregate([ {$project:{ account: "$auditMessages.eventMetaData.Counterparty Name", amount: "$auditMessages.eventMetaData.Transaction Amount", "total": {$sum:"$amount"} }}]) { "_id" : Obj

我想用数组中的字符串类型求总金额，所以我在mongo中写这个。需要帮忙吗

已尝试：

db.compte.aggregate([
 {$project:{
   account: "$auditMessages.eventMetaData.Counterparty Name",
   amount: "$auditMessages.eventMetaData.Transaction Amount",
   "total": {$sum:"$amount"}
 }}])

{
"_id" : ObjectId("5ed638e566a699750cbb1b0f"),
"account" : [
  "Mr Jalel CHAHED",
  "Mr Jalel CHAHED",
  "Mr Jalel CHAHED",
  "Mr Jalel CHAHED"
 ],
"amount" :
 [ 
  "4.32",
  "4.32",
   "1.32",
   "1.32"
 ],
"total" : 0}

db.collection.aggregate([
    {
      $project: {
        account: { $arrayElemAt: [ "$auditMessages.eventMetaData.Counterparty Name", 0 ] }, // get name from first element in array,use only if name is same in all objects
        total: {
          $reduce: {
            input: "$auditMessages.eventMetaData.Transaction Amount", // Iterate on array
            initialValue: 0,
            in: { $trunc: [ { $add: [ "$$value", { $toDouble: "$$this" } ] }, 2 ] } // convert string to double, sum-up & truncate to 2 digits
          }
        }
      }
    }
  ])

结果：

db.compte.aggregate([
 {$project:{
   account: "$auditMessages.eventMetaData.Counterparty Name",
   amount: "$auditMessages.eventMetaData.Transaction Amount",
   "total": {$sum:"$amount"}
 }}])

{
"_id" : ObjectId("5ed638e566a699750cbb1b0f"),
"account" : [
  "Mr Jalel CHAHED",
  "Mr Jalel CHAHED",
  "Mr Jalel CHAHED",
  "Mr Jalel CHAHED"
 ],
"amount" :
 [ 
  "4.32",
  "4.32",
   "1.32",
   "1.32"
 ],
"total" : 0}

db.collection.aggregate([
    {
      $project: {
        account: { $arrayElemAt: [ "$auditMessages.eventMetaData.Counterparty Name", 0 ] }, // get name from first element in array,use only if name is same in all objects
        total: {
          $reduce: {
            input: "$auditMessages.eventMetaData.Transaction Amount", // Iterate on array
            initialValue: 0,
            in: { $trunc: [ { $add: [ "$$value", { $toDouble: "$$this" } ] }, 2 ] } // convert string to double, sum-up & truncate to 2 digits
          }
        }
      }
    }
  ])

您正在

$project

中创建

amount

字段，并在同一阶段使用它本身，这就是为什么它在

“total”上返回0
：{$sum:$amount”}

，而且

$sum

似乎不接受数组

假设您的文档看起来像：

{
    "auditMessages": {
      eventMetaData: [
        {
          "Counterparty Name": "Mr Jalel CHAHED",
          abc: 1,
          "Transaction Amount": "4.32"
        },
        {
          "Counterparty Name": "Mr Jalel CHAHED",
          abc: 11,
          "Transaction Amount": "4.32"
        },
        {
          "Counterparty Name": "Mr Jalel CHAHED",
          abc: 12,
          "Transaction Amount": "1.32"
        },
        {
          "Counterparty Name": "Mr Jalel CHAHED",
          abc: 122,
          "Transaction Amount": "1.32"
        }
      ]
    }
  }

auditMessages.eventMetaData

是一个数组，执行以下操作时：

“$auditMessages.eventMetaData.contractor Name”

或

“$auditMessages.eventMetaData.Transaction Amount”

那么您得到的是一个值数组，就像您现在在结果中看到的值一样

查询：

db.compte.aggregate([
 {$project:{
   account: "$auditMessages.eventMetaData.Counterparty Name",
   amount: "$auditMessages.eventMetaData.Transaction Amount",
   "total": {$sum:"$amount"}
 }}])

{
"_id" : ObjectId("5ed638e566a699750cbb1b0f"),
"account" : [
  "Mr Jalel CHAHED",
  "Mr Jalel CHAHED",
  "Mr Jalel CHAHED",
  "Mr Jalel CHAHED"
 ],
"amount" :
 [ 
  "4.32",
  "4.32",
   "1.32",
   "1.32"
 ],
"total" : 0}

db.collection.aggregate([
    {
      $project: {
        account: { $arrayElemAt: [ "$auditMessages.eventMetaData.Counterparty Name", 0 ] }, // get name from first element in array,use only if name is same in all objects
        total: {
          $reduce: {
            input: "$auditMessages.eventMetaData.Transaction Amount", // Iterate on array
            initialValue: 0,
            in: { $trunc: [ { $add: [ "$$value", { $toDouble: "$$this" } ] }, 2 ] } // convert string to double, sum-up & truncate to 2 digits
          }
        }
      }
    }
  ])

测试：

Ref:

您正在

$project

中创建

amount