DataWeave Basics
By the end of this lesson, you'll be able to:
- Write a simple DataWeave transformation script
- Explain DataWeave's role in a Mule flow
Prerequisites: The Salesforce Connector
What DataWeave does
Two systems rarely agree on data shape — one calls it first_name, another firstName; one wants JSON, another XML. DataWeave sits between processors in a flow, transforming the in-flight message's structure, field names, and format without writing general-purpose code for it.
Basic DataWeave syntax
A script starts with %dw 2.0, declares an output format, then an expression (often an object literal) building the new shape — payload refers to the incoming data, and field access uses dot notation just like many other languages.
Reshaping a payload with DataWeave
%dw 2.0
output application/json
---
{
fullName: payload.firstName ++ " " ++ payload.lastName,
email: payload.emailAddress,
isActive: payload.status == "Active"
}This takes an incoming payload with firstName/lastName/emailAddress/status fields and reshapes it into a differently-named, differently-structured JSON object — a common shape when two systems disagree on field naming.
Exercise
Write a DataWeave script that takes payload.accountName and payload.revenue, and outputs JSON with keys 'name' and 'annualRevenue'.
Show hint
%dw 2.0, output application/json, then an object literal mapping the renamed keys.
DataWeave Basics — Quick Check
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Summary
DataWeave is MuleSoft's functional data transformation language — it reshapes data from one format or structure into another (JSON to XML, one field naming convention to another) between the systems a Mule flow connects.