[hibernate-dev] metamodel branch and javax.persistence.metamodel.Metamodel

[Steve Ebersole]

The background here is integrating my JPA 2.1 work in with the Hibernate 
5.0 metamodel branch.  One of the things the EntityManagerFactory does 
when starting up is to build the JPA 
javax.persistence.metamodel.Metamodel.  Today that process leverages the 
old Hibernate mapping code (org.hibernate.mapping).  I will need to 
re-write this to leverage the new org.hibernate.metamodel code.  I 
wanted to run the way I am thinking of attacking this past everyone to 
get feedback.  Basically I want to have the *SessionFactory* take over 
responsibility for building it.  2 main reasons why:
1) First it would be more efficient.  Today we loop over those mapping 
objects at least twice: once to create the persisters as part of 
SessionFactory building and then again later to build this JPA Metamodel 
as part of EntiytManagerFactory building.  Once is better than twice 
when it comes to looping :)
2) I have this other idea where I'd really like to see JPA criterias 
useable in "native" Hibernate usage (Session/SessionFactory).  Which 
would essentially require both javax.persistence.metamodel.Metamodel as 
well as javax.persistence.criteria.CriteriaBuilder to be available. 
Well technically any "criteria builder" that output the proper types 
could work; and I guess Metamodel is not strictly needed to build 
criterias aside from potentially populating the static generated 
metamodel classes.  But it would be nice to have them.


-- 
steve at hibernate.org
http://hibernate.org