[hibernate-dev] Default access type and MappedSuperclass

[Steve Ebersole]

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
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>> >>
>> >
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