Dataweave 2: Objects and Arrays

Anybody dealing with Dataweave scripts will often come across situations where an Object needs to be converted into an Array or vice-versa. The Dataweave 2 examples below describe how to convert between Objects and Arrays.

Example 1: Converting an Object to an Array

This example uses the core Dataweave function pluck; it is useful in mapping an object into an array, pluck iterates over an object and returns an array of keys, values, or indices from the object. It is an alternative to mapObject, which is similar but returns an object, instead of an array.

Ref: https://docs.mulesoft.com/mule-runtime/4.3/dw-core-functions-pluck

Input:

{
  "key1" : "value1",
  "key2" : "value2",
  "key3" : "value3"
}

Dataweave:

%dw 2.0
output application/json
---
payload pluck ((value, key, index) -> 
{
    "key" : key,
    "value" : value,
    "index" : index
}
)

Output:

[
  {
    "key": "key1",
    "value": "value1",
    "index": 0
  },
  {
    "key": "key2",
    "value": "value2",
    "index": 1
  },
  {
    "key": "key3",
    "value": "value3",
    "index": 2
  }
]

Example 2: Converting an Array to an Object

This example uses the core Dataweave function reduce; it is useful in applying a reduction expression to the elements in an array. For each element of the input array, in order to, reduce applies the reduction lambda expression (function), then replace the accumulator with the new result. The lambda expression can use both the current input array element and the current accumulator value.

Ref: https://docs.mulesoft.com/mule-runtime/4.3/dw-core-functions-reduce

Input: 

[
  {
    "key1": "value1"
  },
  {
    "key2": "value2"
  },
  {
    "key3": "value3"
  }
]

Dataweave:

%dw 2.0
output application/json
---
payload reduce ($ ++ $$)

Output:

{
  "key3": "value3",
  "key2": "value2",
  "key1": "value1"
}

Hope this helps!