Define result of "getResultList" (and others) as never NULL

[Bukama]

Hey everyone,
this is my first time to get in closer contact with the Jakarta Team and as I can't imagine that this topic was never discussed before and I couldn't find an (open or closed) issue/discussion/etc I decided to ask this question/idea here:

The Javadoc of the persistence spec of Query.getResultList() still does not define what (NULL or an empty List) is returned when the result set is empty. So the user either depends on the implemention or has to do an null check when using the method.

For example: In old versions of Hibernate the implementation returned NULL, newer versions (I can't find since when exactly, but have stopped searching as I looked into the current specs first) return an userfriendly empty list.

So I want to suggest to update the specification that such methods are never allowed to return null. I know this might be not backward compatible to older specs, but since Jakarta has begun to release non backward compatible specs I think this is a valid change.

[gavinking]

In old versions of Hibernate the implementation returned NULL

This is simply false. Hibernate always returns an empty list when a query returns no results. And this has been the case since before Hibernate 1.0. No version of Hibernate has ever used null to indicate "no results". You're just mistaken about that.

(I suppose it's possible that you once ran into a bug in some very specific exceptional case.)

I know this might be not backward compatible to older specs

The expectation has always been that getResultList() returns a non-null instance of List.

So we could certainly make this more explicit, but FWIW I think it's always been pretty clear that an empty list is the correct way to represent "no results". Because using null for this would be obviously insane.

[gavinking]

So we could certainly make this more explicit

See proposed change here:

https://github.com/jakartaee/persistence/pull/538/files

[Bukama]

Thank your for your response and your PR!