Looping using dataweave

Question

my input xml:

  <Root>
     <Element>
         <Record att="a">value</Record>
         <Record att="b">value</Record>
           .
           .
          <Record att="g">value</Record>
          <Record att="h">value</Record>
            .
             .
          <Record att="p">value</Record>
            .
            .
          <Record att="t">value</Record>
              .
              .
          <Record att="w">value</Record>
               .
                .
          <Record att="z">value</Record>
     </Element>
     <Element>
         <Record att="a">value</Record>
         <Record att="b">value</Record>
           .
           .
          <Record att="g">value</Record>
          <Record att="h">value</Record>
            .
             .
          <Record att="p">value</Record>
            .
            .
          <Record att="t">value</Record>
              .
              .
          <Record att="w">value</Record>
               .
                .
          <Record att="z">value</Record>
     </Element>
     .
     .
     .
     .
     .
     .
   </Root>

The dataweave configuration I tried:

   %dw 1.0
   %input payload application/xml
   %output application/csv

  ---
  payload.root.*Element[0].*Record map {
    (id:$.@att) when ($.@att) == "g" or ($.@att) == "t", 
    (type:($.@att) when ($.@att) == "g" or ($.@att) == "t"
  }

The o/p i got in my csv:

  id,type (headers)
  blanklines
  .
  .
  .
  g,g
  .
  .
  .
  .
  t,t
  .
  .

The requirement is clear. I need only the Records of Element[0]. My o/p CSV should not have any blank lines. Expected output should be:

    id,type
    g,g
    t,t

I couldnot still understand the syntax and concepts of dataweave for looping. Please help me out. Any better solution is accepted.

Answer 1

If you don't use the subscript it refers to the first element. You can try removing subscript [0]

%dw 1.0
%input payload application/xml
%output application/csv 
---
payload.Root.*Element.*Record map {
    (id:$.@att) ,
    (type:$.@att)
} filter 

Answer 2

How are you accessing a name attribute (@name) as it isn't in your XML? You should access the 'att' attribute right? (@att)

Did you post the correct code and XML ?

OK This should do the job for you.

%dw 1.0
%input payload application/xml
%output application/csv 
---
payload.Root.*Element[0].*Record map {
(id:$.@att) ,
(type:$.@att)
} filter ($.id == "g" or $.type == "t")

Answer 3

script-:1(if you wan to extract only 1st position object values if @att == g or t )

   %dw 2.0
   input payload application/xml
   output application/csv

  ---
  payload.Root.*Element[0].*Record filter( ["t","g"] contains  $.@att) map{
      "id" : $.@att,
      "type" : $.@att
  }

output:-

id,type
g,g
t,t

script-:2(if you wan to extract all the objects values if @att == g or t )

 %dw 2.0
   input payload application/xml
   output application/csv

  ---
  payload.Root.*Element.*Record filter( ["t","g"] contains  $.@att) map{
      "id" : $.@att,
      "type" : $.@att
  }

output:-

id,type
g,g
t,t
g,g
t,t

Answer 4

This code below will work fine

Weave Code
%dw 1.0
%output application/csv
---
payload.Root.*Element[0].*Record filter (($.@att == 'g') or ($.@att == 't')) map {
    (id : $.@att),
    (type : $.@att)
} 

Output

id,type
g,g
t,t