[hibernate-dev] Default access type and MappedSuperclass

[Gunnar Morling]

Yes, we're doing something like that in MapStruct, too:


https://github.com/mapstruct/mapstruct/blob/master/processor/src/main/java/org/mapstruct/ap/MappingProcessor.java#L114

There we need to wait with code generation for processed classes until
their hierarchy has stabilized (other APs may generate superclasses that we
must consider). Perhaps the Code ist helpful to you.

--Gunnar

Am 10.01.2019 15:01 schrieb "Steve Ebersole" <steve at hibernate.org>:

Hm, seems like the "AP delayed generation" approach is a possibility.  From
a quick search:

https://stackoverflow.com/questions/41874462/java-annotation-process-not-yet-generated-elements
https://docs.oracle.com/javase/6/docs/api/javax/annotation/processing/RoundEnvironment.html#processingOver%28%29

Disclaimer - I have not tried this, just read about it...


On Thu, Jan 10, 2019 at 7:18 AM Steve Ebersole <steve at hibernate.org> wrote:

> This is one of the cases (there are others) where we do not completely
> follow the JPA spec.
>
> TBH I'm not really sure how we would address this in an annotation
> processor, though granted my knowledge of those APIs is limited.  But as I
> understand it we have to generate the metamodel class as we process the
> model class without knowledge of or access to other classes.  Specifically
> here, we see the MappedSuperclasss first as it is a superclass and the
> compiler needs to process it first.
>
> I had planned on re-looking at this in 7 to offer a non-AP solution to
> metamodel generation.  I don't think anything requires that we support
this
> through an AP.
>
> There are other problems using an AP for this, namely it is extremely
> difficult to incorporate orm.xml info whether partial or complete.
>
> I guess a solution for now would involve somehow delaying the generation
> of the metamodel classes until the end of the AP cycle which (IIUC) would
> only really work with `proc:only`
>
> On Thu, Jan 10, 2019 at 6:29 AM Guillaume Smet <guillaume.smet at gmail.com>
> wrote:
>
>> The generated model of the MappedSuperclass?
>>
>> Because the one of the subclass is correct for sure.
>>
>> On Thu, Jan 10, 2019 at 12:44 PM andrea boriero <andrea at hibernate.org>
>> wrote:
>>
>> > I'm not sure I have fully understood the issue, the @Id may be not
>> defined
>> > in the MappedSuperclass but for sure it must be in the subclasses
>> extending
>> > it.
>> >
>> > I have tried and I can reproduce the issue only if I do not specify
>> > any @Id annotation in the subclass, but as soon as I add the @Id to a
>> > subclass of the MappedSuperclass the generated static metamodel is
>> correct.
>> >
>> >
>> > On Thu, 10 Jan 2019 at 11:04, Guillaume Smet <guillaume.smet at gmail.com>
>> > wrote:
>> >
>> >> Hi,
>> >>
>> >> We recently had this issue opened about us not choosing the right
>> access
>> >> type for a mapped super class:
>> >> https://hibernate.atlassian.net/browse/HHH-12938 .
>> >>
>> >> Hibernate currently base the access type decision on the sole
>> placement of
>> >> the @Id annotation, which, in the case of a @MappedSuperclass might
>> not be
>> >> defined (this is the OP's case).
>> >>
>> >> I closed the issue explaining what we do and pointing a workaround but
>> the
>> >> OP rightfully replied with the JPA spec saying "The default access
>> type of
>> >> an entity hierarchy is determined by the placement of mapping
>> annotations
>> >> on the attributes of the entity classes and mapped superclasses of the
>> >> entity hierarchy that do not explicitly specify an access type".
>> >>
>> >> I'm wondering if we should also consider the @Column annotations
>> placement
>> >> if there is no @Id annotation.
>> >>
>> >> If the answer is that it's already fixed in 6, it's all good for me
:).
>> >>
>> >> Thoughts?
>> >>
>> >> --
>> >> Guillaume
>> >> _______________________________________________
>> >> hibernate-dev mailing list
>> >> hibernate-dev at lists.jboss.org
>> >> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>> >>
>> >
>> _______________________________________________
>> hibernate-dev mailing list
>> hibernate-dev at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>
>
_______________________________________________
hibernate-dev mailing list
hibernate-dev at lists.jboss.org
https://lists.jboss.org/mailman/listinfo/hibernate-dev