Transformation of Json array in Dataweave - mule

Question

How to write Dataweave transformation in Anytime Studio for given input and output of Json array.
Input:
{
"result": [{
"Labels": [{
"value": [{
"fieldName": "firstName",
"value": "John"
},
{
"fieldName": "lastName",
"value": "Doe"
},
{
"fieldName": "fullName",
"value": "John Doe"
}
]
}]
}]
}
Output:
{
"result": [{
"Labels": [{
"value": [{
"firstName": "John",
"lastName": "Doe",
"fullName": "John Doe"
}]
}]
}]
}
https://docs.mulesoft.com/dataweave/2.4/dw-core-functions-reduce Reduce function might be the one should be used
Thank you in advance

Answer 1

You can just use map to map all the arrays to required format. For the value part you can map the values as fieldName: value array and deconstruct them to an object by wrapping the array around parentheses
%dw 2.0
output application/json
---
{
result: payload.result map ((item) -> {
Labels: item.Labels map ((label) -> {
value: [
{
(label.value map ((field) ->
(field.fieldName): field.value
)) //wrap the array, i.e. lavel.value map ... in parentheses so that it will give you individual key pair.
}
]
})
})
}

Answer 2

You can try below if you are aware that the keyNames will not change:
%dw 2.0
output application/json
---
payload update {
case res at .result -> res map (res, resIndex) -> (res update {
case lbl at .Labels -> lbl map (lbl, lblIndex) -> (lbl update {
case val at .value -> [
(val reduce ((item, acc = {}) -> acc ++ {
(item.fieldName): (item.value)
}))
]
}
)
}
)
}

Answer 3

Here's 2 caveats and a solution. Your input and output files, both are not valid JSON.
Input file, in your "result" object, "Labels" need curly braces {} since they are objects. Key-value pairs should look like this {key:value} not like that key:value
Output file, inside your "value" arrays, key-value pairs need to have the curlies {key:value}
So here's a valid JSON version of your input
{
"result": [
{"Labels": [
{
"value": [
{"fieldName": "firstName","value": "John"},
{"fieldName": "lastName","value": "Doe"},
{"fieldName": "fullName","value": "John Doe"}
]
}
]},
{"Labels": [
{
"value": [
{"fieldName": "firstName","value": "John"}
]
}
]}
]}
Here's a solution
%dw 2.0
import keySet from dw::core::Objects
// this is "result"
var layer1key = keySet(payload)[0]
// this is "Labels" and grabs the first Labels, so assumes Labels doesn't change
var layer2 = payload[layer1key]
var layer2key = keySet(layer2[0])[0]
// this is "value"
var layer3 = layer2[layer2key]
var layer3key = keySet(layer3[0][0])[0]
// this is "fieldName" and "value"
var layer4 = layer3 map (x) -> x['value']
var data1 = ((layer1key) : layer4 map (x) -> {
(layer2key): x map (y) -> {
(layer3key): y map (z) -> {
(z['fieldName']):z['value']
}
}
})
output application/json
---
data1
And a valid JSON version of your output
{
"result": [
{
"Labels": [
{
"value": [
{
"firstName": "John"
},
{
"lastName": "Doe"
},
{
"fullName": "John Doe"
}
]
}
]
},
{
"Labels": [
{
"value": [
{
"firstName": "John"
}
]
}
]
}
]
}