在 Dataweave 中，选择器 .. 和 .* 有什么区别？

Question

我看到文档说

Multi-value  .*keyName  Array of values of any matching keys
Descendants  ..keyName  Array of values of any matching descendant keys

但是我还是不明白其中的区别

Answer 1

我觉得很容易喜欢用例子来解释，所以根据this one你会得到下一个结果：

payload.breakfast_menu.food -> First food element

payload.breakfast_menu.*food -> List of food elements

payload.breakfast_menu.*name -> Nothing

payload.breakfast_menu..name -> List of all product name values

Answer 2

后代 returns 对象的每个嵌套级别中第一次出现的键的数组。多值 returns 对象的当前嵌套级别中出现的所有键的数组。

如果你有这样的输入：

{
    "id": 1,
    "id": 11,
    "secondLevel": {
        "id": 2,
        "id": 22,
        "thirdLevel": {
            "id": 3,
            "id": 33
        }
    }
}

还有这个脚本：

%dw 2.0
output application/json
---
{ 
    "descendant": payload..id, //first occurrence of "id" in each level
    "multivalue": payload.*id, //all occurrence of "id" in the current level (the first level)
    "multivalueSecondLevel": payload.secondLevel.*id, //all occurrence of "id" in the current level (the second level)
    "allTheIds" : payload..*id //all the ID (descendant with multivalue)
}

它将生成此输出：

{
  "descendant": [
    1,
    2,
    3
  ],
  "multivalue": [
    1,
    11
  ],
  "multivalueSecondLevel": [
    2,
    22
  ],
  "allTheIds": [
    1,
    11,
    2,
    22,
    3,
    33
  ]
}

更多详情见https://docs.mulesoft.com/mule-runtime/4.2/dataweave-cookbook-extract-data#descendants

在 Dataweave 中，选择器 .. 和 .* 有什么区别？

In Dataweave what is the difference between the selector .. and .*?

dataweave

mulesoft