Fix need for registerAssociationAttribute

[mkotsbak]

From the sample:

  // Hibernate seems to generate incorrect metamodel data for some types of
  // associations, so we have to manually supply the correct information here.
  streams.registerAssociationAttribute(Lineorder.class.getMethod("getSale"), "sale", false);

Why is this, and is it solvable? With this requirement for all relations it seems, it is not practical to use Jinq with JPA. Maybe it is possible to get it from the @onetomany etc. annotations?

[my2iu]

Jinq already automatically reads in all the JPA relation information from the Criteria API metamodel. Hibernate has a small bug with @ ManyToOne relations where that information is incorrect, so you have to manually supply the correct information for those cases. For all other relations, Jinq reads it all in automatically.

[mkotsbak]

Hmm, why is JPA queries working fine then? Isn't it using the same metamodel?

Is it working better with EclipseLink?

[my2iu]

The Criteria API metamodel is just a mechanism that Hibernate uses to expose its model to the outside for people using the Criteria API. Hibernate's internal representation is probably fine, but things get mixed up when it exports it to the outside. I don't think anyone really uses it much, so they never really bothered fixing the bug in this one corner case of ManyToOne associations (OneToMany associations work fine, oddly enough). I don't have a support contract with them, so I don't even know how to file bugs against it. Even if the data that Hibernate provides in this metamodel data is wrong, everything else seems to work fine internally with Hibernate (well, it works fine to the extent that Hibernate normally works fine internally).

That particular corner case works fine in EclipseLink, but EclipseLink has bugs in other corner cases. Basically, all the JPA providers seem to have different bugs for different corner cases. Jinq tends to give them a workout in codepaths that aren't typically exercised.

[mkotsbak]

Ah, thanks for the explanation. Yes, the criteria API is quite ugly, so I guess not many people are using it.

I would suggest reporting the bug in Hibernate here: https://hibernate.atlassian.net/projects/HHH