quarkusio/quarkus · error · RuntimeException

should only extend REST Data Panache interface

Error message

 should only extend REST Data Panache interface

What it means

A REST Data Panache resource interface may only extend a single REST Data Panache interface (e.g. PanacheMongoRepositoryResource); extending anything else would make the generated method set ambiguous. The processor enforces this by counting interfaceNames.

Source

Thrown at extensions/panache/hibernate-reactive-rest-data-panache/deployment/src/main/java/io/quarkus/hibernate/reactive/rest/data/panache/deployment/HibernateReactivePanacheRestProcessor.java:135

            String resourceClass = resourceImplementor.implement(
                    classOutput, dataAccessImplementor, resourceInterface, entityType, listenersForEntityType);
            // Make sure that repository bean is not removed and will be injected to the generated resource
            unremovableBeansProducer.produce(new UnremovableBeanBuildItem(
                    new UnremovableBeanBuildItem.BeanClassNameExclusion(repositoryClassName)));

            restDataResourceProducer.produce(new RestDataResourceBuildItem(
                    new ResourceMetadata(resourceClass, resourceInterface, entityType, idType,
                            getEntityFields(index, entityType))));
        }
    }

    private void validateResource(IndexView index, ClassInfo classInfo) {
        if (!Modifier.isInterface(classInfo.flags())) {
            throw new RuntimeException(classInfo.name() + " has to be an interface");
        }

        if (classInfo.interfaceNames().size() > 1) {
            throw new RuntimeException(classInfo.name() + " should only extend REST Data Panache interface");
        }

        if (!index.getKnownDirectImplementors(classInfo.name()).isEmpty()) {
            throw new RuntimeException(classInfo.name() + " should not be extended or implemented");
        }
    }

    private List<Type> getGenericTypes(ClassInfo classInfo) {
        return classInfo.interfaceTypes()
                .stream()
                .findFirst()
                .orElseThrow(() -> new RuntimeException(classInfo.toString() + " does not have generic types"))
                .asParameterizedType()
                .arguments();
    }
}

View on GitHub (pinned to e1c734241f)

Solutions

1. Keep the annotated resource interface extending exactly one REST Data Panache interface
2. Move any extra interface inheritance to a repository or service class instead
3. Add custom endpoints via separate CDI beans/JAX-RS resources rather than extra interfaces

Example fix

// before
@PanacheRepositoryResource
public interface CustomerResource extends PanacheMongoRepositoryResource<CustomerRepository, Customer, Long>, Serializable {}
// after
@PanacheRepositoryResource
public interface CustomerResource extends PanacheMongoRepositoryResource<CustomerRepository, Customer, Long> {}

if (Arrays.stream(CustomerResource.class.getInterfaces()).count() != 1)
    throw new IllegalStateException("Resource interface must extend exactly one REST Data Panache interface");

When it happens

Trigger: An interface annotated with a REST Data Panache annotation extends more than one interface (e.g. both a Panache resource interface and another unrelated interface).

Common situations: Adding a custom interface to share extra method contracts with resource interfaces; refactoring that merged resource interfaces with application interfaces.

Related errors

• ${classInfo.name()} has to be an interface
• ${classInfo.name()} should only extend REST Data Panache int
• ${classInfo.name()} should not be extended or implemented
• has to be an interface
• Couldn't find id field of ${classInfo}

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/48404e2caafe197e. Report an issue: GitHub.