I'm heavily using the polymorphic features but I need a stable library
so I will stick with 0.4 for now.
Thank you!
David
Michael Bayer napsal(a):
> oh, that. OK, in the 0.4 series you'd want to set
> "polymorphic_fetch='deferred'" on your mapper. Just leave it that
> way, as the "non-deferred" behavior has been removed from 0.5 anyway
> (its deferred in all cases). The second table will be fetched as
> needed.
>
> if you're depending heavily on inheritance I strongly recommend
> looking at 0.5, this is one area where a significant amount of work
> has been done.
>
> On Aug 25, 2008, at 11:24 AM, ml wrote:
>
>> This is not working:
>>
>> Setup:
>> --------------------------------------------------------------------
>> base = Table("base", metadata,
>> Column("id", Integer, primary_key=True),
>> Column("kind", Integer),
>> )
>>
>> derived = Table("derived", metadata,
>> Column("id", Integer, ForeignKey("base.id"), primary_key=True)
>> )
>>
>> class Base(object): pass
>> class Derived(Base): pass
>>
>> mapper(Base, base,
>> polymorphic_on=base.c.kind,
>> polymorphic_identity=0,
>> )
>>
>> mapper(Derived, derived,
>> inherits=Base,
>> polymorphic_identity=1,
>> )
>> --------------------------------------------------------------------
>>
>> and this call:
>> session.query(Base).with_polymorphic(Base).first()
>>
>> will still result in 2 SELECTs and the returned object is Derived
>> (tables are filled only with Derived objects)
>>
>> SELECT base.id AS base_id, base.kind AS base_kind
>> FROM base ORDER BY base.id
>> LIMIT 1 OFFSET 0
>>
>> SELECT derived.id AS derived_id
>> FROM derived
>> WHERE %(param_1)s = derived.id
>>
>> <__main__.Derived object at 0xce1b10>
>>
>> SQLAlchemy version 0.4.7p1
>>
>> I need only 1 SELECT and Base object returned.
>>
>>
>>
>> Michael Bayer napsal(a):
>>> call with_polymorphic passing in only the base class:
>>>
>>> query.with_polymorphic(BaseClass).filter()....
>>>
>>>
>>> On Aug 25, 2008, at 10:35 AM, ml wrote:
>>>
>>>> Hi!
>>>>
>>>> How can I disable a polymorphic load for a single query? I found a
>>>> hint
>>>> in http://markmail.org/message/2kwbm377j3pdvvqb but I can't find
>>>> more.
>>>>
>>>> Thanks for any advice.
>>>>
>>>> David
>>>>
>>>
>
>
> >
>
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