MuleSoft Dataweave 减少

Question

我尝试了解 Mulesoft Dataweave 2.0 中的归约函数。

预期结果：

{
  "dev": "1",
  "test": "2",
  "uat": "3",
  "prod": "4"
}

我的数据编织代码：

%dw 2.0
var invar = [
  {"id": "1", "name": "dev"},
  {"id": "2", "name": "test"},
  {"id": "3", "name": "uat"},
  {"id": "4", "name": "prod"}
]
output application/json
---
// invar reduce() ???  requirment: it must be done with reduce function.

谢谢

Answer 1

技巧是当 DataWeave 无法自动推导累加器时将其设置为正确的值：

%dw 2.0
var invar = [
  {"id": "1", "name": "dev"},
  {"id": "2", "name": "test"},
  {"id": "3", "name": "uat"},
  {"id": "4", "name": "prod"}
]
output application/json
---
invar reduce ((item, accumulator= {}) -> accumulator ++ {(item.name):item.id})

Answer 2

将累加器初始化为空对象{}，并将形成的键值对添加到累加器中以获得所需的输出：

invar reduce ((item, accumulator = {}) -> accumulator ++ {(item.name): item.id } )

Answer 3

Reduce 适用于数组，并不断累积每次数组迭代，并在处理完成后返回。在您的示例中，我使用空对象 {} 初始化累加器，并且在每次迭代中，我使用 item.name 作为对象键，使用 item.id 作为值。

var invar = [
  {"id": "1", "name": "dev"},
  {"id": "2", "name": "test"},
  {"id": "3", "name": "uat"},
  {"id": "4", "name": "prod"}
]
output application/json
---
invar reduce ((item, accumulator={}) -> accumulator ++ {
    (item.name) : item.id
})

Answer 4

%dw 2.0
var invar = [
  {"id": "1", "name": "dev"},
  {"id": "2", "name": "test"},
  {"id": "3", "name": "uat"},
  {"id": "4", "name": "prod"}
]
output application/json
---
invar reduce ((item, acc = {}) -> acc ++ {(item.name) : item.id})