Conditionally Reduce a List through a Function

This DataWeave example flattens the input to something simpler. For each element in the input, it conditionally includes a contentTypes field only in case it has any values. It then rearranges this content into a more readable shape. Before you begin, note that 2.x versions of DataWeave are used by Mule 4 apps. For DataWeave in Mule 3 apps, refer to DataWeave version 1.2 examples. For other DataWeave versions, you can use the version selector in the DataWeave table of contents.

The examples use these functions:

map to go through every element in the input array.
reduce to aggregate the multiple elements in the tags array into one field.
splitBy to parse the values in the "tags" array, so as to only select the first part of each string (through [0]) and discard the second.
++ to concatenate these elements into one single string, with commas as separators.
if include the last field only if the contentTypes array is bigger than 0.

DataWeave Script:

%dw 2.0
output application/json
fun reduceMapFor(data) = data reduce(($$ splitBy ":")[0] ++ "," ++ ($ splitBy ":")[0])
---
payload.results map
    {
        email: $.profile.email,
        name: $.profile.firstName,
        tags: reduceMapFor($.data.interests.tags[0]),
        (contenttypes: reduceMapFor($.data.interests.contenttypes[0])) if (sizeOf($.data.interests.contenttypes[0]) > 0)
    }

Input JSON Payload:

{
  "results": [
    {
      "profile": {
        "firstName": "john",
        "lastName": "doe",
        "email": "johndoe@demo.com"
      },
      "data": {
        "interests": [
          {
            "language": "English",
            "tags": [
              "digital-strategy:Digital Strategy",
              "innovation:Innovation"
            ],
            "contenttypes": []
          }
        ]
      }
    },
    {
      "profile": {
        "firstName": "jane",
        "lastName": "doe",
        "email": "janedoe@demo.com"
      },
      "data": {
        "interests": [
          {
            "language": "English",
            "tags": [
              "tax-reform:Tax Reform",
              "retail-health:Retail Health"
            ],
            "contenttypes": [
              "News",
              "Analysis",
              "Case studies",
              "Press releases"
            ]
          }
        ]
      }
    }
  ],
  "objectsCount": 2,
  "totalCount": 2,
  "statusCode": 200,
  "errorCode": 0,
  "statusReason": "OK"
}

Output JSON:

[
  {
    "email": "johndoe@demo.com",
    "name": "john",
    "tags": "digital-strategy,innovation"
  },
  {
    "email": "janedoe@demo.com",
    "name": "jane",
    "tags": "tax-reform,retail-health",
    "contenttypes": "News,Analysis,Case studies,Press releases"
  }
]

Conditionally Reduce a List through a Function

Related Examples

See Also