How to declare function in dataweave?

You can declare a function in the header or body of a DataWeave script by using the fun keyword.

Declaration of a function in data weave is as follows:

fun function_Name(objParameter) = { 
Variable1: objParameter.field1, 
Variable2: objParameter.field2 
} 

You can simply Invoke the function by using functionName() or functionName(arg1, arg2, argN).