[hibernate-dev] Pull request for HHH-2394 (Support filter tag in subclass)

[Rob Worsnop]

On Mon, Jun 4, 2012 at 12:14 PM, Steve Ebersole <steve at hibernate.org> wrote:
> 1) I think adding support for {alias} is a more general issue.  Its
> applicable to many other pieces of mapping metadata (@Formula, etc).  More I
> was responding to David's comment there.  I totally think it makes sense to
> support this in all of those cases.  I guess the vote point there is whether
> we want to introduce that support piecemeal or develop it across the board.
>  If we do do it piecemeal I think another piece of information we will need
> is a flag indicating whether to scan for alias injection points.  By
> "scanning" I mean the processing we do today where we tokenize the fragment
> string and then try to guess where an alias is needed.   Let's call this
> flag 'deduceAliasInjectionPoints' for now.  I tend to favor meaningful
> attribute names so my suggested names tend to get a little long; I am open
> to suggestions for a more succinct name.  Anyway, I think it needs to be
> TRUE by default to maintain backwards compatible behavior.  Here is an
> example:
>
> @Filter(name="iqMin", table="ZOOLOGY_HUMAN", condition="{alias}.HUMAN_IQ >=
> :min", deduceAliasInjectionPoints=false)
>
> Here there is no need to deduce the points at which to inject an alias; we
> have done that for Hibernate in the supplied condition fragment.
>
> I think another discussion revolves around cases in which the fragment
> involves references to columns from multiple tables.  Mostly this is
> important for scenarios involving secondary tables and inheritance.  Do we
> want to provide support for that?  Using the classic
> org.hibernate.test.hql.Animal hierarchy from the testsuite, maybe something
> like:
>
> @Filter(
>   name="iqMin",
>   condition="{a}.bodyWeight >= :minWeight and {m}.birthdate <
> :ageCutOffBirthDate",
>   deduceAliasInjectionPoints=false,
>   aliases={
>       @SqlFragmentAlias( alias="a", entity=Animal.class ),
>       @SqlFragmentAlias( alias="m", entity=Mammal.class )
>   }
> )
>

How about just applying the secondary table usage to everything?

So, to rewrite your first example:

@Filter(name="iqMin", condition="{h}.HUMAN_IQ >=> :min",
    aliases={@SqlFragmentAlias( alias="h", table="ZOOLOGY_HUMAN" )})

Note that I didn't include "deduceAliasInjectionPoints". Wouldn't we
just infer that from the presence of the aliases element?