How to select last duplicate object in array of objects in Mule 4

Question

There is an array of duplicate objects(same id) from which last repeated object needs to be selected. Input:

{ 
    "message": [
        { 
            "name": "Abc", 
            "address":"Mumbai",
            "phone":"91-1234567891",
            "id":123
        }, 
        { 
            "name": "Pqr", 
            "address":"Pune",
            "phone":"91-1234985438",
            "id":456
        }, 
        { 
            "name": "Abc",
            "address":"Delhi",
            "phone":"91-1234567891",
            "id":123
        }
    ]
}

Expected Output:

{
  "message": [
    {
      "name": "Pqr",
      "address": "Pune",
      "phone": "91-1234985438",
      "id": 456
    },
    {
      "name": "Abc",
      "address": "Delhi",
      "phone": "91-1234567891",
      "id": 123
    }
  ]
}

In output, it should take the last repeated object values. I tried distinctBy function on id field but it picks random object from duplicates. Any help would be appreciated. Thank you.

Answer 1

You can try the following DataWeave expression:

%dw 2.0
output application/json
---
{
    "message": payload.message groupBy ((item, index) -> item.id) 
        pluck ((value, key, index) -> value) 
            map ((item, index) -> item[sizeOf(item) - 1])
}

Input:

{ 
    "message": [
        { 
            "name": "Abc", 
            "address":"Mumbai",
            "phone":"91-1234567891",
            "id":123
        }, 
        { 
            "name": "Pqr", 
            "address":"Pune",
            "phone":"91-1234985438",
            "id":456
        }, 
        { 
            "name": "Abc",
            "address":"Delhi",
            "phone":"91-1234567891",
            "id":123
        }
    ]
}

Output:

{
  "message": [
    {
      "name": "Abc",
      "address": "Delhi",
      "phone": "91-1234567891",
      "id": 123
    },
    {
      "name": "Pqr",
      "address": "Pune",
      "phone": "91-1234985438",
      "id": 456
    }
  ]
}