Javascript Mongo-基于名称的值和的聚合

我试图执行一个聚合函数，根据名称值计算成本和利润值之和。因此，如果多个结果的名称为“假供应商”，我需要成本结果和利润结果的总和

查询语句：

Pharmacy.aggregate([
{
  $match: {
    $and: [{ 'prescription.status': 'Ready for Pickup' }]
  }
},
{
  $project: {
    'insurance.primary.name': 1,
    'prescription.financial.cost': 1,
    'prescription.financial.margin': 1
  }
}
])

结果类似于：

[
  {
      "_id": "5cab98cd293bd54e94c40461",
      "insurance": {
          "primary": {
              "name": "Fake Provider 1"
          }
      },
      "prescription": [
          {
              "financial": {
                  "cost": "2.89",
                  "margin": "5.60"
              }
          },
          {
              "financial": {
                  "cost": "0.88",
                  "margin": "1.24"
              }
          }
      ]
  },
  {
      "_id": "5cab98d0293bd54e94c40470",
      "insurance": {
          "primary": {
              "name": "Fake Provider 1"
          }
      },
      "prescription": [
          {
              "financial": {
                  "cost": "3.22",
                  "margin": "9.94"
              }
          },
          {
              "financial": {
                  "cost": "2.57",
                  "margin": "9.29"
              }
          },
          {
              "financial": {
                  "cost": "2.03",
                  "margin": "10.17"
              }
          }
      ]
  }
]

 [
{
  "primaryInsurance": "Fake Provider 1",
  "totalFinancialCost": "11.59",
  "totalFinancialMargin": "36.24"
},
{
  "primaryInsurance": "Fake Provider 2",
  "totalFinancialCost": "12.82",
  "totalFinancialMargin": "22.16"
}
]

我试图创建一个组语句，但运气不好。此外，成本和利润值当前存储为字符串

  $group: {
    _id: '$insurance.primary.name',
    Financial: {
      $push: {
        id: '$insurance.primary.name',
        name: '$insurance.primary.name',
        cost: '$prescription.financial.cost',
        margin: '$prescription.financial.margin'
      }
    }
  }

我希望得到与以下类似的结果：

[
  {
      "_id": "5cab98cd293bd54e94c40461",
      "insurance": {
          "primary": {
              "name": "Fake Provider 1"
          }
      },
      "prescription": [
          {
              "financial": {
                  "cost": "2.89",
                  "margin": "5.60"
              }
          },
          {
              "financial": {
                  "cost": "0.88",
                  "margin": "1.24"
              }
          }
      ]
  },
  {
      "_id": "5cab98d0293bd54e94c40470",
      "insurance": {
          "primary": {
              "name": "Fake Provider 1"
          }
      },
      "prescription": [
          {
              "financial": {
                  "cost": "3.22",
                  "margin": "9.94"
              }
          },
          {
              "financial": {
                  "cost": "2.57",
                  "margin": "9.29"
              }
          },
          {
              "financial": {
                  "cost": "2.03",
                  "margin": "10.17"
              }
          }
      ]
  }
]

 [
{
  "primaryInsurance": "Fake Provider 1",
  "totalFinancialCost": "11.59",
  "totalFinancialMargin": "36.24"
},
{
  "primaryInsurance": "Fake Provider 2",
  "totalFinancialCost": "12.82",
  "totalFinancialMargin": "22.16"
}
]

---

我想我有一个解决方案，可以使用查找和投影返回结果，然后使用javascript映射结果并执行添加。但是，我更喜欢在数据库级别执行此操作。

您必须首先展开“处方”字段，然后执行组。尝试此管道：

let pipeline = [
{
  $unwind: {
    path: '$prescription'
  }
},
{
  $group: {
    _id: '$insurance.primary.name',
    totalFinancialCost: {
      $sum: { $convert: { input: '$prescription.financial.cost', to: "decimal" } } 
    },
    totalFinancialMargin: {
      $sum: { $convert: { input: '$prescription.financial.margin', to: "decimal" } } 
    }
  }
}]

---

请注意如何将值转换为十进制以执行求和。

我收到此错误-MongoError:无法识别的表达式“$convert”。看起来我使用的是v3.6.3。此版本中可能不可用。请尝试使用以下语句：$sum:{$toDecimal:'$prescription.financial.margin'}MongoError:无法识别的表达式“$toDecimal”仅在版本4.0中可用。如果在版本3.6.3中不可能，我将升级，然后重试。转换函数在版本4.0后可用，因此请更新或更改数据类型。