JPA Retrieving Outbound Gateway produced no reply when zero entities in database

[menno.j]

If a JPA Retrieving Outbound Gateway is configured using entity-class and there are no entities in the database then it seems to produce no reply for the original request message. The log states:

DEBUG o.s.i.j.outbound.JpaOutboundGateway - handler 'org.springframework.integration.jpa.outbound.JpaO utboundGateway@9fb4679' produced no reply for request Message

I expected it to send a reply message with an empty list. Without this, it means the receiver (in my case another gateway) is just blocking waiting for a reply. Adding a timeout to the receiving gateway is unsatisfactory, because then how do I distinguish between a genuine database delay, and the use case where there are no entities in the database?

Have I missed some config setting that resolves this?

Thanks,
Menno

[Gary Russell]

Looks like a bug to me - I believe that the gateway should, as you say, return an empty list if there are no results. A gateway should never behave this way.

It gets a bit more tricky if 'expectSingleResult' is true (we can't return a null payload), so I suspect we'd have to return an empty list there too - but that's a bit messy because the result type will depend on the data. Maybe we'd have to throw an exception in that case.

Please go ahead and create a JIRA ticket and we can start a dialog of how to fix the problem there.