[hibernate-dev] Naming strategies 4.3 -> 5.0

[Gail Badner]

See below...

On Sat, Aug 15, 2015 at 7:25 AM, Steve Ebersole <steve at hibernate.org> wrote:

> I think I may have goofed when I implemented some of the
> ImplicitNamingStrategy rules in 5.0.
>
> During that transition, I wrote a bunch of unit test in 4.3 to serve as a
> baseline to make sure I got the logic/rules right as I developed 5.0.  But
> I think I may have set up those initial 4.3 tests improperly.
> Specifically, there are a few meant to test Hibernate's legacy naming
> behavior, aka its non-JPA-compliant naming.
>
> I think I got confused by the whole concept of NamingStrategy and
> NamingStrategyDelegate and NamingStrategyDelegator that had gotten added to
> 4.3.
>
> So on 4.3, what is the proper way to specify Hibernate should use
> JPA-compliant implicit naming?  What is the proper way to specify that it
> should use its legacy naming?
>

This is well-documented at:
http://docs.jboss.org/hibernate/orm/4.3/manual/en-US/html_single/#configuration-namingstrategy

There are also some properties that are available for use with Entity
Manager (only documented in
http://docs.jboss.org/hibernate/orm/4.3/manual/en-US/html_single/#configuration-misc-properties
):
- hibernate.ejb.naming_strategy
-hibernate.ejb.naming_strategy_delegator


>
> The issue came to light via HHH-9908.  Consider a mapping like:
>
> @Entity
> @Table(name = "ptx")
> public class Ptx {
>
>     @Id
>     private Integer id;
>
>     @ManyToMany
>     private List<Input> inputs1;
>
> }
>

>
> Assuming that Inputs defines its primary table as "input", the
> JPA-compliant naming would be "ptx_input".  That is what happens on 4.3
> using EJB3NamingStrategy.  It is actually also what happens on master using
> ImplicitNamingStrategyJpaCompliantImpl.
>
> However, the "legacy" part I cannot figure out.  Unless I misremember, back
> in the day we used to interpret these based on the attribute name, rather
> than the associated table name.  So here we'd have "ptx_inputs1".  That is
> in fact what ImprovedNamingStrategy does on 4.3.  But I
> believe ImprovedNamingStrategy is not the default on 4.3.  Again, between
> NamingStrategy and NamingStrategyDelegate and NamingStrategyDelegator it is
> VERY hard to understand what it going on, so maybe I just missed
> something.  Anyway, on 4.3 setting no naming strategy forces this to behave
> in a JPA-compliant way, meaning the implicit name here is "ptx_input" when
> I do not specify anything for NamingStrategy(Delegat(e/or)).  So either
> that got screwed up in 4.2/4.3 (whenever those new indirections where
> added) or I simply misremember what we used to do here.
>

Are you talking about the generated table name, or the foreign key name? I
see that the test case attached to HHH-9908 uses Spring. Do you have a test
case for this that does not use Spring?

HHH-9390 fixed a bug when generating the default foreign key name in a
unidirectional many-to-many that refers to the owner.

Ih JSR 388, 2.10.5.2 Unidirectional ManyToMany Relationships:

"Entity A is mapped to a table named A.
Entity B is mapped to a table named B.
There is a join table that is named A_B (owner name first). This join table
has two foreign key columns. One foreign key column refers to table A and
has the same type as the primary key of table A. The name of this foreign
key column is formed as the concatenation of the following: the name of
entity A; " _"; the name of the primary key column in table A. The other
foreign key column refers to table B and has the same type as the primary
key of table B. The name of this foreign key column is formed as the
concatenation of the following: the name of the relationship property or
field of entity A; " _ "; the name of the primary key column in table B"

The legacy behavior differed for the first FK:
"The name of this foreign key column is formed as the concatenation of the
following: the name of entity A; " _"; the name of the primary key column
in table A."

The legacy behavior was to use the table name (not the entity name).

The JPA-compliant behavior is provided by
ImprovedNamingStrategyDelegator#jpaNamingStrategyDelegate,
which, by default, is of type JpaNamingStrategyDelegate. It will properly
use the entity name.

This difference is illustrated in
org.hibernate.test.annotations.manytomany.defaults.DefaultNamingManyToManyTest#testUnidirOwnerEntityNamePrimaryTableOverride
and extended by ImprovedManyToManyDefaultsTestFor (this was done before you
mentioned your strong dislike for testing using inheritance...):

As far as I know, collection table naming and the other FK (that references
the associated entity) were unchanged by my fixes.

Also, the spec wrt the join table name and FKs for bidirectional
many-to-many is different from unidirectional. I did not find any problems
with how Hibernate was generating the join table or FKs for bidirectional
many-to-many.

If there is a specific case that doesn't look right, please create a test
case that reproduces it and I'll take a look.

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