Custom Validation Error Not Displayed in Extend App (PMD Binding Typo)
What it means
An Extend app calling a Workday web service to create a business process transaction, like a Requisition, gets back only a generic validation-error message instead of the specific custom validation text that Workday shows when the same transaction is submitted through the standard UI. The Extend app's PMD isn't correctly extracting the individual error details from the response.
Troubleshooting
- Confirm the underlying transaction genuinely triggers a custom validation in Workday by testing it directly in the standard UI first, so you know the error text you're trying to surface actually exists in the response payload.
- Check the PMD's outboundData responseErrorDetail block and the binding expression used to map error attributes, since a single incorrect function name here silently degrades the error handling to a generic message instead of throwing a scripting error.
- Compare the binding expression against Workday's documented list function names; mapAttributes (plural) and mapAttribute (singular) look nearly identical but are different functions, and using the wrong one on a list can cause the response mapping to fail silently.
- Inspect the raw web service response outside the Extend app to confirm the actual validation error text is present in the payload before assuming the problem is upstream.
Correct the binding expression in the PMD's responseErrorDetail block from the plural list function to the correct singular one, save, and redeploy the app.
Add a PMD code review step, or a simple test transaction with a known validation failure, to your Extend app's deployment checklist specifically to confirm custom error messages surface correctly, since this class of typo doesn't throw a build error and only shows up when a real validation failure occurs in production.