Dataweave Cheatsheet (v1.0)

Reference: https://docs.mulesoft.com/mule-user-guide/v/3.9/dataweave

$$: key / index

$: value

@: Create or reference XML attribute

%output application/dw: Outputs the cannonical datamodel of DataWeave

Object:

{
  key: "value"
}

Array:

%dw 1.0
%output application/json
---
[ "elem1", "elem2", "elem3" ]

Map operator:

%dw 1.0
%output application/json
---
shirts: payload map {
        size: upper $.size,
        description: $.description,
        count: $.count
}

Constants and functions (%var):

%dw 1.0
%var prefix = 'The destination is: '
%var append = (param1, param2) ->  param1 ++ param2
%var createFlightCodeElement = (code) -> flightCode: code
%var createDestinationCodeElement = (dest) -> destinationCode: dest
%output application/xml
---
flights: {(payload map {
	flight @(flightCode: $.code):
	{	
		destination: append(prefix, $.destination),
        code: createFlightCodeElement($.code),
        dest: createDestinationCodeElement($.destination)
	}
 })
}

XML attribute in output
Input	Transformation	Output
[{ "ID": 1, "code": "ER38sd", "destination": "SFO", "plane": { "type": "Boeing 737", "totalSeats": 150 } }, { "ID": 2, "code": "ER45if", "destination": "LAX", "plane": { "type": "Boeing 777", "totalSeats": 300 } }]	%dw 1.0 %output application/xml --- flights: {(payload map { flight @(flightCode: $.code): { destination: $.destination } }) }	<?xml version='1.0' encoding='windows-1252'?> <flights> <flight flightCode="ER38sd"> <destination>SFO</destination> </flight> <flight flightCode="ER45if"> <destination>LAX</destination> </flight> </flights>
Item index in the output ("$$")
Input	Transformation	Output
[{ "ID": 1, "code": "ER38sd", "destination": "SFO", "plane": { "type": "Boeing 737", "totalSeats": 150 } }, { "ID": 2, "code": "ER45if", "destination": "LAX", "plane": { "type": "Boeing 777", "totalSeats": 300 } }]	%dw 1.0 %output application/xml --- flights: {(payload map { flight @(index: $$): { code: $.code } }) }	<?xml version='1.0' encoding='windows-1252'?> <flights> <flight index="0"> <code>ER38sd</code> </flight> <flight index="1"> <code>ER45if</code> </flight> </flights>