Mule 4：DW 转换：如何在 XML 中连接嵌套节点的值？答案

【问题标题】：Mule 4 : DW transformation : How to concatenate the values of a nested node in XML?Mule 4：DW 转换：如何在 XML 中连接嵌套节点的值？
【发布时间】：2021-06-13 22:28:50
【问题描述】：

场景：从以下 XML 中，将学生的分数和科目与“-”连接起来，并将其作为 JSON 输出。

输入：

<StudentsData>
    <Student name="ABC" rollnumber="123">
        <Subject name="Maths" marks="90" Sem="1st"/>
        <Subject name="Eng" marks="67" Sem="1st"/>
        <Subject name="Physics" marks="54" Sem="1st"/>
        <Subject name="Chemitry" marks="77" Sem="1st"/>
        <Subject name="Biology" marks="89" Sem="1st"/>
    </Student>
    <Student name="DEF" rollnumber="123">
        <Subject name="Maths" marks="87" Sem="1st"/>
        <Subject name="Eng" marks="89" Sem="1st"/>
        <Subject name="Physics" marks="88" Sem="1st"/>
        <Subject name="Chemitry" marks="55" Sem="1st"/>
        <Subject name="Biology" marks="87" Sem="1st"/>
    </Student>
</StudentsData>

预期输出

[
  {
    "Name": "ABC",
    "Sub1": "Maths-90",
    "Sub2" : "Eng-67",
    "Sub3" : "Physics-54",
    "Sub4" :  "Chemitry-77",
    "Sub5" : "Biology-89"
  },
  {
    "Name": "DEF",
    "Sub1": "Maths-87",
    "Sub2" : "Eng-89",
    "Sub3" : "Physics-88",
    "Sub4" :  "Chemitry-55",
    "Sub5" : "Biology-87"
  }
]

我想做什么：

%dw 2.0
output application/json
fun concatenateMarksAndSubject(items) = (items reduce ((item, accumulator = []) ->
    accumulator << (item.@name ++ "|" ++ item.@marks)
      )) 
---
payload.StudentsData.*Student map ((student, index) -> {
    "Name": student.@name,
     "Sub$(index)" :  concatenateMarksAndSubject(student.*Subject)
} )

请帮忙。提前致谢

【问题讨论】：

标签： dataweave mule4

【解决方案1】：

此脚本产生预期的结果。

%dw 2.0
output application/json
fun concatenateMarksAndSubject2(items) = 
    items 
        mapObject ((value, key, index) -> (value.@name): value.@marks ) 
        pluck ((value, key, index) -> "Sub$(index)": key ++ "-" ++ value )
---
payload.StudentsData.*Student map ((student, index) -> {
    "Name": student.@name,
     (concatenateMarksAndSubject2(student))
} )

【讨论】：

成功了，非常感谢。在 map 和 reduce 之间，我多次忘记了 mapObject 方法。这将是一个值得记住的好用例 :-)