Mule 4 dataweave 2.0 mapping nested array logic

Question

I am getting below JSON request

[{
"Weight": "787.00",
"Volume": "65.00",
"TrackID": "128260490",
"item": [
  {
    "Description": "basketball",
    "totalquantity": 1
  },
  {
    "Description": "football",
    "totalquantity": 4
  }
  ]
 },
 {
"Weight": "68.200",
"Volume": "44.298",
"TrackID": "890433466",
"item": [
  {
    "Description": "hockeystick",
    "totalquantity": 8
  }
  ]
 }
]

and I am looking output (in json format only) in below manner:

    { 
     Purchasedetails: [
     {
     "TrackID": 128260490,
    "Description": "basketball",
     "totalquantity": 1
     },
    {
     "TrackID": 128260490,
     "Description": "football",
    "totalquantity": 4
     },
    {
    "TrackID": 890433466,
    "Description": "hockeystick",
    "totalquantity": 8
    }
   ]
}

Here if you see closely same tracking id is coming in basketball and football (description) as they have common TrackID, how can I handle this TrackID logic?

Answer 1

Try this:

%dw 2.0
output application/json
---
// Create the object with the PurchaseDetails field
{
    // Iterate over every single object in the array
    // NOTE: I prefare reduce because it saves iterations and/or array removals
    PurchaseDetails: payload reduce (  
        (pd, result=[]) -> (
            // Append the array of items with the TrackID to the result
            result ++ (
                // Build a new object for each object in the item array
                pd.item map { 
                    // Add the TrackID to the resulting object
                    TrackID: pd.TrackID,
                    ($)
                }
            )
        )
    )
}