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DataWeave 2.2 is compatible and bundled with Mule 4.2. This version of Mule reached its End of Life on May 2, 2023, when Extended Support ended.

Deployments of new applications to CloudHub that use this version of Mule are no longer allowed. Only in-place updates to applications are permitted.

MuleSoft recommends that you upgrade to the latest version of Mule 4 that is in Standard Support so that your applications run with the latest fixes and security enhancements.

underscore(String): String

Replaces hyphens, spaces, and camel-casing in a string with underscores.

If no hyphens, spaces, and camel-casing are present, the output will match the input.


Name Description


The input string.


This example replaces the hyphens and spaces in the input. Notice that the input "customer" is not modified in the output.


%dw 2.0
import * from dw::core::Strings
output application/json
   "a" : underscore("customer"),
   "b" : underscore("customer-first-name"),
   "c" : underscore("customer NAME"),
   "d" : underscore("customerName")


   "a": "customer",
   "b": "customer_first_name",
   "c": "customer_name",
   "d": "customer_name"

underscore(Null): Null

Helper function that allows underscore to work with null values.