🎮 DataWeave Playground

Table of Contents

• ✨ Features
• 🚀 Getting Started
  • Prerequisites
  • Installation
• 📁 Project Structure
• 🎯 Playground Workflow
  • 🧭 Current Development Flow
  • 🎯 How It Mirrors the Online Playground
• 📦 Available Modules
  • 📅 DateFormatConversionModule
  • 🔧 Mule
  • 🎮 main.dwl
• 🧪 Testing
  • 🧪 Testing Strategies
    • 1️⃣ Interactive Playground Workflow
    • 2️⃣ Unit Tests (Testing Framework)
  • 🏃 Running Tests
  • 📊 Test Reports
• 🔍 Preview Like Playground
  • Prerequisites
  • How to Use
• 🎯 Usage Examples
  • Example 1: Transform JSON Payload
  • Example 2: Date Formatting with Module
  • Example 3: Working with Mule Runtime Objects
• 🏗️ Creating New Modules
  • Step 1: Create the Module File
  • Step 2: Create a Test Mapping
  • Step 3: Add Test Input (Optional)
  • Step 4: Run Your Test
• 📚 Documentation Standards
  • Function Documentation Template
  • 📝 Naming Conventions
• 🌐 Publishing to Exchange
  • Prerequisites
  • Enable Exchange Publishing
  • Publish
• 🤝 Contributing
• 📄 License
• 🔗 Resources
• Notes About Includes

A local, version-controlled alternative to the MuleSoft DataWeave Playground - develop, test, and share DataWeave transformations offline.

✨ Features

Feature	Online Playground	This Project
🔌 Offline Development	❌	✅
📂 Version Control (Git)	❌	✅
🤖 AI (Copilot, Claude, Antigravity, etc)	❌	✅
🔄 CI/CD Integration	❌	✅
💻 Full IDE Support	❌	✅
📦 Reusable Module Libraries	❌	✅
🏢 Enterprise Formats (Excel, FlatFile, Avro)	❌	✅
🚀 Publish to Exchange	❌	✅
🧪 Automated Unit Testing	❌	✅
⚡ Quick Experimentation	✅	✅
🛠️ Custom Module Creation	✅	✅
🎮 Mimics Online Playground Experience	✅	✅
🆓 Free and Open Source	✅	✅

🚀 Getting Started

Prerequisites

• ☕ Java 8+ (JDK installed and JAVA_HOME configured)

• Tools to manage multiple JDK versions:

  • scoop

  • SDKMAN

  • jabba

• 📦 Maven 3.6+

• 🛠️ IDE (VS Code with Anypoint Code Builder recommended)

Installation

git clone https://github.com/andersoal/mule-dataweave-playground
cd mule-dataweave-playground

📁 Project Structure

playground/
|-- pom.xml
|-- README.md
|-- README.adoc
`-- src/
    |-- main/
    |   |-- dw/
    |   |   |-- DateFormatConversionModule.dwl
    |   |   |-- Mule.dwl
    |   |   `-- main.dwl
    |   `-- resources/
    |       `-- properties.yaml
    `-- test/
        |-- dw/
        |   `-- DateFormatConversionModuleTest.dwl
        `-- resources/
            |-- DateFormatConverstionModuleMapping/
            |   `-- Playground/inputs/payload.json
            `-- main/
                `-- Playground/inputs/
                    |-- attributes.dwl
                    |-- correlationId.dwl
                    |-- error.dwl
                    |-- payload.dwl
                    `-- vars.dwl

🎯 Playground Workflow

This repository currently uses src/main/dw/main.dwl as the closest equivalent to the online DataWeave playground.

Online Playground	Local Project
Main Editor Panel	src/main/dw/main.dwl
Reusable snippets	src/main/dw/*.dwl modules
Input Panel	src/test/resources/main/Playground/inputs/
Output Panel	DataWeave: Run Preview or Maven test output

🧭 Current Development Flow

1. Edit src/main/dw/main.dwl for quick experiments.

2. Use Mule::p(…​) from Mule.dwl when you need mock property access.

3. Move reusable logic into dedicated modules under src/main/dw/.

4. Add assertion-based tests under src/test/dw/ when logic needs regression coverage.

🎯 How It Mirrors the Online Playground

Online Playground	Local Project
Quick experimentation	src/main/dw/main.dwl + preview inputs
Reusable modules	src/main/dw/*.dwl
Automated validation	src/test/dw/*.dwl unit tests
Auto Preview with DataWeave Extension	Use DataWeave: Enable Auto Preview in VS Code

📦 Available Modules

📅 DateFormatConversionModule

Location: src/main/dw/DateFormatConversionModule.dwl

Utilities for date and time formatting conversions.

link:src/main/dw/DateFormatConversionModule.dwl[role=include]

🔧 Mule

Location: src/main/dw/Mule.dwl

Utilities for Mule runtime property access simulation.

link:src/main/dw/Mule.dwl[role=include]

🎮 main.dwl

Location: src/main/dw/main.dwl

This is the current playground entrypoint for local experimentation.

link:src/main/dw/main.dwl[role=include]

🧪 Testing

🧪 Testing Strategies

This project currently supports two complementary workflows.

1️⃣ Interactive Playground Workflow

Use src/main/dw/main.dwl together with the fixtures in src/test/resources/main/Playground/inputs/.

link:src/test/resources/main/Playground/inputs/payload.dwl[role=include]

link:src/test/resources/main/Playground/inputs/attributes.dwl[role=include]

link:src/test/resources/main/Playground/inputs/vars.dwl[role=include]

link:src/test/resources/main/Playground/inputs/error.dwl[role=include]

link:src/test/resources/main/Playground/inputs/correlationId.dwl[role=include]

2️⃣ Unit Tests (Testing Framework)

link:src/test/dw/DateFormatConversionModuleTest.dwl[role=include]

Fixture data for mapping-style experiments:

link:src/test/resources/DateFormatConverstionModuleMapping/Playground/inputs/payload.json[role=include]

🏃 Running Tests

mvn test
mvn test -Dtest=DateFormatConversionModuleTest
mvn clean test

📊 Test Reports

After running tests, reports are generated in:

target/data-weave-test-reports/

🔍 Preview Like Playground

The Anypoint Code Builder extension for VS Code provides real-time preview capabilities for DataWeave mappings.

Prerequisites

• 🔧 Anypoint Code Builder - DataWeave Extension

• 📄 Input files under src/test/resources/main/Playground/inputs/

How to Use

1. Open src/main/dw/main.dwl

2. Run DataWeave: Run Preview from the Command Palette

3. Enable DataWeave: Enable Auto Preview for instant refresh on save

🎯 Usage Examples

Example 1: Transform JSON Payload

%dw 2.0
output application/json
---
payload.users map (user) -> {
    fullName: user.firstName ++ " " ++ user.lastName,
    email: lower(user.email)
}

Example 2: Date Formatting with Module

%dw 2.0
import dateTimeConversion from DateFormatConversionModule
output application/json
---
{
    timestamp: dateTimeConversion(now(), "yyyy-MM-dd'T'HH:mm:ss"),
    readable: dateTimeConversion(now(), "MMMM dd, yyyy")
}

Example 3: Working with Mule Runtime Objects

%dw 2.0
output application/json
---
{
    data: payload,
    requestId: correlationId,
    headers: attributes.headers,
    customVar: vars.myVariable,
    hello: Mule::p("example.hello")
}

🏗️ Creating New Modules

Step 1: Create the Module File

%dw 2.9
// src/main/dw/StringUtilsModule.dwl

fun titleCase(text: String): String =
    text splitBy " "
    map (word) -> upper(word[0]) ++ lower(word[1 to -1])
    joinBy " "

fun removeWhitespace(text: String): String =
    text replace /\s+/ with ""

Step 2: Create a Test Mapping

%dw 2.0
// src/test/dw/StringUtilsMapping.dwl
import * from StringUtilsModule
output application/json
---
{
    titleCaseResult: titleCase("hello world"),
    noWhitespace: removeWhitespace("hello world")
}

Step 3: Add Test Input (Optional)

{
  "text": "hello dataweave playground"
}

Step 4: Run Your Test

mvn test -Dtest=StringUtilsMapping

📚 Documentation Standards

Function Documentation Template

/**
 * Brief description of what the function does.
 */
fun myFunction(param: Type): ReturnType = ...

📝 Naming Conventions

Type	Convention	Example
Modules	PascalCase + Module suffix	StringUtilsModule.dwl
Test Mappings	PascalCase + Mapping suffix	StringUtilsMapping.dwl
Unit Tests	PascalCase + Test suffix	StringUtilsModuleTest.dwl
Functions	camelCase	formatDate(), parseJson()

🌐 Publishing to Exchange

Share your modules with others by publishing to Anypoint Exchange.

Prerequisites

1. Anypoint Platform account with Exchange contributor permissions

2. Configure credentials in ~/.m2/settings.xml

<server>
    <id>exchange</id>
    <username>your-username</username>
    <password>your-password</password>
</server>

Enable Exchange Publishing

Replace the placeholder organization id in pom.xml, then uncomment the Exchange configuration.

link:pom.xml[role=include]

Publish

mvn deploy -Dproject.groupId=your-organization-id

🤝 Contributing

1. 🍴 Fork the repository

2. 🌿 Create a feature branch (git checkout -b feature/amazing-module)

3. 💾 Commit your changes (git commit -m 'Add amazing module')

4. 📤 Push to the branch (git push origin feature/amazing-module)

5. 🔃 Open a Pull Request

📄 License

This project is for development and learning purposes.

🔗 Resources

• 📘 DataWeave Documentation

• 🎮 Online DataWeave Playground

• 📦 Anypoint Exchange

• 🧪 DataWeave Testing Framework

Notes About Includes

This document intentionally references project files via include:: so code samples stay synchronized with source.

If you render this file with Asciidoctor locally, includes are expanded automatically.

Made with ❤️ for the MuleSoft Community