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.

%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:

%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:

Here is testing data:

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