REST Resource Extensions

Generated REST resources are standard classes. You can extend or wrap them when you need custom REST behaviour.

Typical Extensions

1. Add custom endpoints alongside the generated /process
2. Override exception mapping
3. Inject additional services for cross-cutting concerns

1. Add a custom endpoint alongside /process

Use a thin wrapper resource when you want a bespoke route without replacing the generated processing entrypoint.

@Path("/payments")
@ApplicationScoped
public class PaymentResourceExtension {
    @Inject
    ProcessPaymentResource generatedResource;

    @POST
    @Path("/process")
    public Uni<Response> process(PaymentRecordDto input) {
        return generatedResource.process(input);
    }

    @GET
    @Path("/health-summary")
    public Response healthSummary() {
        return Response.ok(Map.of("status", "ok")).build();
    }
}

2. Override exception mapping

Replace or extend the generated exception mapper when you need domain-specific HTTP status codes or payloads.

@Provider
public class PaymentFailureMapper implements ExceptionMapper<PaymentValidationException> {
    @Override
    public Response toResponse(PaymentValidationException error) {
        return Response.status(Response.Status.BAD_REQUEST)
            .entity(Map.of("code", "payment-validation", "message", error.getMessage()))
            .build();
    }
}

3. Inject a cross-cutting service

Inject a dedicated service for audit, tracing, tenancy, or feature-flag decisions and keep the controller thin.

@ApplicationScoped
public class RequestAuditService {
    public void record(String routeName, String correlationId) {
        // Send audit event or metric here.
    }
}

@Path("/payments")
@ApplicationScoped
public class PaymentResourceExtension {
    @Inject
    RequestAuditService auditService;

    @POST
    @Path("/preview")
    public Response preview(@HeaderParam("X-Correlation-ID") String correlationId) {
        auditService.record("payments-preview", correlationId);
        return Response.accepted().build();
    }
}