That is a great point about components. Thinking components should
really be handled just like we propose for entities. Especially if we
allow inheritance hierarchies with components (which I would love to do
generally and to account for here specifically).
<properties/> itself poses a problem. It can contain associations, but
can also be the basis for defining an association. In this respect they
are just like components. So maybe we need to handle them then same as
we do for components.
Collections are associations, and would just be handled in that phase
whatever their collection type or element type.
On 06/13/2011 07:02 PM, Gail Badner wrote:
Components and properties (as in<properties>) can have embedded
to-one associations.
Would these be processed during 4 (attribute), with any embedded associations deferred
until 5 (associations)?
What about value collections? Would they be included in 4 (attributes)?
----- Original Message -----
From: "Steve Ebersole"<steve(a)hibernate.org>
To: hibernate-dev(a)lists.jboss.org
Sent: Monday, June 13, 2011 2:29:41 PM
Subject: [hibernate-dev] Processing mapping information followup
Wanted to start a follow up discussion to the conversation we had at the
IRC meeting on 6/13 with regards to changing the way we process mapping
information to follow dependencies in the various types of information.
What we do currently (in the metamodel code) is essentially the same as
the legacy code. That is to say we process through a mapping source in
full and then move on to the next one, saving off "second passes"
whenever we encounter information on which we have to wait. The second
passes in the new metamodel code are isolated I guess (so far) to
org.hibernate.metamodel.source.internal.EntityReferenceResolver
What I proposed instead is quite different, more like what I did for the
rest of the MetadataImpl constructor code in terms of defining
dependencies and processing stuff in an order that makes sure to avoid
the need for second passes.
Here is the initial swab at the levels of information:
1) entity - basic entity information such as name, hierarchy
2) identifiers - normal identifiers could almost be handled in the first
level. key-many-to-one still needs some form of delayed queuing.
3) secondary tables
4) attributes
5) associations
The dependencies flow downward; (2) depends on (1); (3) depends on (2); etc.
I liked handling (3) secondary tables separately because they basically
expand the possible set of columns available for (4) and (5).
--
Steve Ebersole <steve(a)hibernate.org>
http://hibernate.org