Create sub array in dataweave 2

Question

I have a json meesage and want to get the below output. Input message:

[
{
 Header:{
id:12,
dept: HR
},
details:[
{ 
 lineid: 1234,
 acc : "ABC"
},
{ 
 lineid: 98745,
 acc : "cba"
}]
}]

expected output:

[
 {
 "id": 12,
 "lineid": 1234},
 {
 "id": 12,
 "lineid": 98745
 }
]

used dataweave:

%dw 2.0
output application/json
---


 payload  map ( payload01 , indexOfPayload01 ) -> {

((payload01.Header map ( payload02, indexOfPayload02 ) -> {
    id: payload01.Header.id,
    lineid: payload02.lineid
} 

) )
} 

My Output looks fine only the issue is that the value is not coming under sub array i.e.

[ { "id": 12 "lineid": 1234, "id": 12, "lineid": 98745 } ]

Answer 1

Hi I see two things in your script One is that the inner map should be details and not Header (I imagine this is a copy paste or problem simplification issue when copying it into stackoverflow as it doesn't work otherwise). The other problem is the use of { with an expressions enclosed with (

{    
     (
        (payload01.Header map ( payload02, indexOfPayload02 ) -> {
            id: payload01.Header.id,
            lineid: payload02.lineid
        }) 
     )
}

This kind of syntax expands the array inside the object see https://docs.mulesoft.com/mule-runtime/4.1/dataweave-types#dynamic_elements

So if you change it to

payload map ((payload01, indexOfPayload01) -> 
  payload01.details map (payload02, indexOfPayload02) -> {
    id: payload01.Header.id,
    lineid: payload02.lineid
  })

It produces

[
  [
    {
      "id": 12,
      "lineid": 1234
    },
    {
      "id": 12,
      "lineid": 98745
    }
  ]
]