Mule 4 : Dataweave 2 In Action - Use Function Modules

Introduction

In Mule 4, the mel2 functionalities are replaced by the Dataweave 2 ones. For those who worked in Mule 3, you will find the mule 4 ways of using function modules are much more advanced than the old way (see my post). In this article, I am going to present Mule 4 ways to define and use global functions.

Define Functions In Dataweave Modules

Here is my project layout:

As you can see, I place the function modules in the dir: src/main/resources/modules. And the dataweave function module is defined in CommonFunc.dwl.

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%dw 2.0 fun concatName(aPerson) = aPerson.firstName ++ ' ' ++ aPerson.lastName   fun stringToDateUTC(dateString) = ((dateString as String {format: "yyyy-MM-dd'T'HH:mm:ss.SSSZ"} >> "UTC"  )) as DateTime {format: "yyyy-MM-dd'T'HH:mm:ss.SSS"}

I defined two functions: concatName, stringToDateUTC. The purposes are self-explained.

Use Function Modules

I place the normal dataweave modules in the dir of src/main/resources/dataweave. The usage of the functions is demonstrated at the following dwl file:

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%dw 2.0 import * from modules::CommonFunc output application/json --- {  "Name" : concatName(payload),  "CreatedDate" : stringToDateUTC(payload.createdDate) }

Here are few points:

• import functions
1. import modules::CommonFuc
2. import * from modules::CommonFunc
3. import concatName stringToDateUTC from modules::CommonFunc
• use functions in dwl
1. CommonFunc::concatName(payload)
2. concatName(payload)

For those who know python, you may find the syntax is very similar between the two languages, in terms of modules, and references.

Testing Data

Here is the complete flow:

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<flow name="use-functionsFlow" doc:id="ccb2b5cc-b78f-4db2-9337-f96fed2de729">  <http:listener doc:name="Listener" doc:id="e13b3ae1-ac0c-4200-badf-0acb5039efe1" config-ref="HTTP_Listener_config" path="/mule4/func/one">   <ee:repeatable-file-store-stream>  </ee:repeatable-file-store-stream></http:listener>  <ee:transform doc:name="Use Global Functions" doc:id="be1466e6-6c0d-44c3-b876-c191b5a0b2a3">   <ee:message>    <ee:set-payload resource="dataweave/useFunctionModules.dwl">   </ee:set-payload></ee:message>  </ee:transform>  <logger level="INFO" doc:name="Logger" doc:id="9c689ad2-f9bd-47ec-86ba-8d6a7d278e88" message="#[payload]" category="mule4-datweave-in-action"> </logger></flow>

Here is testing data:

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{  "firstName" : "Gary",  "lastName" : "Liu",  "createdDate":"2018-07-17T16:18:03+00:00" }