在Dataweave中，选择器..和。*之间有什么区别？

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

但是我仍然不明白区别。

Answer 1

[我认为喜欢使用示例进行解释很容易，因此基于this one，您将获得下一个结果：

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

多值返回一个数组，该数组包含在对象的当前嵌套级别中所有出现的键。后代返回在对象的每个嵌套级别中第一次出现的键的数组

如果有此输入：

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

和此脚本：
{ 
    "allTheId" : payload..*id, //all the ID
    "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)
}

它将生成此输出：
{
  "allTheId": [
    1,
    11,
    2,
    22,
    3,
    33
  ],
  "descendant": [
    1,
    2,
    3
  ],
  "multivalue": [
    1,
    11
  ],
  "multivalueSecondLevel": [
    2,
    22
  ]
}

https://docs.mulesoft.com/mule-runtime/4.2/dataweave-cookbook-extract-data#descendants中的更多详细信息