在 Dataweave 2.0 中如何从平面数组创建嵌套数组 - Mule 4答案

【问题标题】：In Dataweave 2.0 how to create nested array from flat array - Mule 4在 Dataweave 2.0 中如何从平面数组创建嵌套数组 - Mule 4
【发布时间】：2021-06-11 07:57:40
【问题描述】：

我需要使用从不同 API 收到的响应创建一个嵌套数组。我有这个包含所有数据的平面数组。什么是创建嵌套数组的最佳方法，其中子项根据其结果状态嵌套到其父项。

输入 JSON 平面数组如下：

  [
   {
    "studentNumber": "FP5500",
    "studentName": "John Doe",
    "Subject": "Arts",
    "grade": "B",
    "result": "Pass"
   },{
    "studentNumber": "FP5501",
    "studentName": "Jane Doe",
    "Subject": "Arts",
    "grade": "B",
    "result": "Pass"
   },{
    "studentNumber": "FP5501",
    "studentName": "Jane Doe",
    "Subject": "Economics",
    "grade": "A",
    "result": "Pass"
   },{
    "studentNumber": "FP5502",
    "studentName": "Bane Doe",
    "Subject": "Arts",
    "result": "Fail"
   }
]

期望输出为嵌套数组，如下格式：

[
  {
   "studentNumber": "FP5500",
   "studentName": "John Doe",
   "Status": "Pass",
   "reportDetails": {
     "Subject": "Arts",
     "grade": "B"
    }
  },
  {
   "studentNumber": "FP5501",
   "studentName": "Jane Doe",
   "Status": "Pass",
   "reportDetails": [{
     "Subject": "Arts",
     "grade": "B"
    },
    {
     "Subject": "Economics",
     "grade": "A"
    }]
  } 
]

数组中的第四个元素 (3rd student) 应该被忽略，因为 "result" 是 "Fail"，但是前两个学生应该被包含在响应中，应该只有 "StudentName" => Jane Doe 条目，其中包含用于主题详细信息的嵌套数组。

我进行了研究，但找不到有效的解决方案（不使用 for 或 foreach 循环）。我尝试使用 mapObject 对重复地图进行地图和过滤，但没有进展。我该如何解决？

【问题讨论】：

标签： arrays nested dataweave mulesoft mule4

【解决方案1】：

快速简便的方法如下：

脚本

%dw 2.0
output application/json
---
[payload filter $.result != "Fail" groupBy $.studentNumber   mapObject {
    "studentNumber": $.studentNumber[0],
    "studentName":  $.studentName[0],
    "Subject": $.Subject[0],
    "Status": $.result[0],
    (if (sizeOf($) == 1)
     "reportDetails": ($ map {
        "Subject": $.Subject,
        "Grade": $.grade
    
    })[0]
    else
    "reportDetails": $ map {
        "Subject": $.Subject,
        "Grade": $.grade
    
    })
    
}]

输出

[
  {
    "studentNumber": "FP5500",
    "studentName": "John Doe",
    "Subject": "Arts",
    "Status": "Pass",
    "reportDetails": {
      "Subject": "Arts",
      "Grade": "B"
    },
    "studentNumber": "FP5501",
    "studentName": "Jane Doe",
    "Subject": "Arts",
    "Status": "Pass",
    "reportDetails": [
      {
        "Subject": "Arts",
        "Grade": "B"
      },
      {
        "Subject": "Economics",
        "Grade": "A"
      }
    ]
  }
]

【讨论】：

【解决方案2】：

已接受答案的脚本输出似乎与 OP 的预期输出不匹配。不知道为什么这是被接受的答案。

这是另一个脚本 -

%dw 2.0
output application/json
---
(payload filter ((student) -> student.result == 'Pass') 
    groupBy ((student) -> student.studentNumber))
        pluck $ 
            reduce (item, accumulator= []) -> 
                accumulator ++ [(item[0] - "grade" - "Subject" - "result") 
                    ++ {Status: item[0].result, resultDetails: item map {Subject: $.Subject, grade: $.grade}}]

生产-

[
  {
    "studentNumber": "FP5500",
    "studentName": "John Doe",
    "Status": "Pass",
    "resultDetails": [
      {
        "Subject": "Arts",
        "grade": "B"
      }
    ]
  },
  {
    "studentNumber": "FP5501",
    "studentName": "Jane Doe",
    "Status": "Pass",
    "resultDetails": [
      {
        "Subject": "Arts",
        "grade": "B"
      },
      {
        "Subject": "Economics",
        "grade": "A"
      }
    ]
  }
]

【讨论】：

接受的答案与最初帖子中的要求相匹配。
好的，我没有看到最初的帖子。谢谢。