DataWeave 2.1 is compatible with Mule 4.1. Standard Support for Mule 4.1 ended on November 2, 2020, and this version of Mule will reach its End of Life on November 2, 2022, when Extended Support ends.

Deployments of new applications to CloudHub that use this version of Mule are no longer allowed. Only in-place updates to applications are permitted.

MuleSoft recommends that you upgrade to the latest version of Mule 4 that is in Standard Support so that your applications run with the latest fixes and security enhancements.

flatMap(Array<T>, (item: T, index: Number) -> Array<R>): Array<R>

Applies a transformation function to each element in a list (array) and then flattens the result.

Instead of returning an array of arrays (as map does), it returns a flattened array (see the flatten function).


Name Description


The list (Array type) to map.


The item and/or index in the list to flatten.


This example returns an array containing each index and item in order. Note that you can also write the example like this: { "users" : ["joe", "pete", "matt"] flatMap ([$$ as String, $]) }


%dw 2.0
output application/json
{ "users" : ["joe", "pete", "matt"] flatMap (item, index) -> ([index as String, item]) }


   "users": [

flatMap(Null, (item: Nothing, index: Nothing) -> Any): Null

Helper function that allows flatMap to work with null values.

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