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

[Steve Ebersole]

'deduceAliasInjectionPoints' is important when you don't have 
injections.  Otherwise Hibernate ends up scanning the condition 
fragment for no reason.

On Fri 22 Jun 2012 11:09:31 AM CDT, Rob Worsnop wrote:
> 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?

--
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