Studio MVEL Returns No Conversion for TreeMap$Values When Accessing Multiple Report Services
What does "There is no conversion for the evaluation return type" mean in Workday Studio?
An MVEL expression returned a collection of integration service objects where Studio expected a single value it could turn into a string. The convenience accessor that fetches a report service by alias only ever reaches the first one, so asking for the collection directly hands back every service at once.
Quick fix
Convert the collection so it can be indexed and pull out the one element you need, for example turn intsys.integrationServices.values() into a list and take the element at the position you want, then call the accessor on that single instance instead of on the collection.
Permanent fix
Treat multiple report services as an ordered list from the start: index into the collection explicitly, or filter it by type before selecting, rather than relying on the single-alias accessor in any integration configured with more than one report service. Where you can, give each report service a distinct alias and select by alias, so the logic does not depend on collection ordering, which is not guaranteed to stay stable across deployments.
Troubleshooting
- Confirm the expression is returning a collection rather than one instance. Anything that prints as 'java.util.TreeMap$Values' or arrives wrapped in square brackets is a collection, not a scalar.
- Count what is actually in the integration by evaluating intsys.integrationServices.values().size() in the Studio debugger. A result greater than 1 means the alias-based accessor is not sufficient on its own.
- Check whether the listed objects are a mix of types. A mixture of ParsedIntegrationService and ReportService entries means the collection holds more than just the report services you want, so you cannot simply take the first element.
- Convert the collection into an indexable form before selecting from it, then read the single instance rather than the whole set.
- Re-run and confirm the log now prints a value instead of an object dump.