Dataweave：如何连接 json 数组中某个键的值

Question

我的输入是

[
  {
    "Id": 5,
    "FirstName": "ALEX",
    "LastName": "JOHNSON"
  },
  {
    "Id": 4,
    "FirstName": "BOB",
    "LastName": "BROWN"
  },
  {
    "Id": 2,
    "FirstName": "JANE",
    "LastName": "DOE"
  },
  {
    "Id": 1,
    "FirstName": "JOHN",
    "LastName": "SMITH"
  },
  {
    "Id": 6,
    "FirstName": "JOHN",
    "LastName": "WILKINS"
  },
  {
    "Id": 3,
    "FirstName": "TIMOTHY",
    "LastName": "WALTERS"
  }
]

我想要的输出是一个字符串，按照它们在输入中列出的顺序连接所有 FirstName 值

"ALEX, BOB, JANE, JOHN, JOHN, TIMOTHY"

我是 Dataweave 的新手，不知道该怎么做
提前致谢

Answer 1

一种方法是首先将每个元素映射到 FirstName 值，然后使用 joinBy() 函数将它们连接起来，用逗号分隔：

%dw 2.0
output application/json
---
payload map $.FirstName joinBy  ", "

您也可以使用 reduce() 函数。

Answer 2

你也可以尝试使用后代选择器

%dw 2.0
output application/json
---
payload..FirstName joinBy ","

Dataweave：如何连接 json 数组中某个键的值

Dataweave: How to concatenate values for a certain key in json array

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