Hi, I tried this, but then it selects "WHERE <table>.type IN (NULL)" :(
class NonPolymorphicClass(MyBaseClass):
__mapper_args__ = {
'concrete' : True
}
I'll try some more things, like overriding the __new__ method on the base
class, to create subclasses if they are available, and instances of the
base class if not.
Thank you very much anyway :)
Pau.
2014-03-17 15:44 GMT+01:00 Michael Bayer <mike...@zzzcomputing.com>:
> maybe make a subclass of the polymorphic base, and just put __concrete__ =
> True in the mapper_args. skip the non primary part.
>
>
>
>
> On Mar 17, 2014, at 8:45 AM, Pau Tallada <tall...@pic.es> wrote:
>
> Hi,
>
> Can it be done in declarative?
> I've tried several ways, but I cannot find a working one :/
> Basically, I think I need to redefine some self-referential relationships,
> as they link against the polymorphic class.
>
>
> Meta = declarative_meta()
>
> class NonPolymorphicClass(MyBaseClass):
> __mapper_args__ = {
> 'non_primary' : True
> }
>
> ==> ArgumentError: Inheritance of non-primary mapper for class '
> NonPolymorphicClass' is only allowed from a non-primary mapper
>
>
>
>
> class NonPolymorphicClass(MyBaseClass):
> __table__ = MyBaseClass.__table__
> __mapper_args__ = {
> 'non_primary' : True
> }
>
> ==> ArgumentError: Inheritance of non-primary mapper for class '
> NonPolymorphicClass' is only allowed from a non-primary mapper
>
>
>
>
> class NonPolymorphicClass(Meta):
> __mapper_args__ = {
> 'non_primary' : True
> }
>
> ==> InvalidRequestError: Class <class '__main__.NonPolymorphicClass'>
> does not have a __table__ or __tablename__ specified and does not inherit
> from an existing table-mapped class.
>
>
>
>
> class NonPolymorphicClass(Meta):
> __mapper_args__ = {
> 'non_primary' : True
> }
>
> ==> InvalidRequestError: Class <class '__main__.NonPolymorphicClass'> has
> no primary mapper configured. Configure a primary mapper first before
> setting up a non primary Mapper.
>
>
> 2014-03-17 13:09 GMT+01:00 Pau Tallada <tall...@pic.es>:
>
>> Great!
>>
>> I think it works for my needs :D
>>
>> Thank you very much!
>>
>> Pau.
>>
>>
>> 2014-03-17 12:28 GMT+01:00 Michael Bayer <mike...@zzzcomputing.com>:
>>
>>
>>> On Mar 17, 2014, at 6:48 AM, Pau Tallada <tall...@pic.es> wrote:
>>>
>>> Hi everyone :)
>>>
>>> I have an application with some kind of dynamic model.
>>> Several plugins define subclasses of a common base class and override
>>> their behaviour, but they do not change any column.
>>>
>>> In some scenarios, not all the puglins are loaded, so not all the
>>> subclasses are present/defined in the Metadata, but I still need to query
>>> those instances and access their columns.
>>>
>>> Is there any option/feature/trick to temporarily disable polymorphism in
>>> a single query (or globally for a session or engine) and load all classes
>>> as instances of the base class?
>>>
>>>
>>>
>>> you can use a non primary mapper:
>>>
>>> m = mapper(MyBase, my_base_table, non_primary=True)
>>>
>>> s.query(m).all()
>>>
>>>
>>>
>>>
>>> The other option is to hack some kind of on-demand polymorphism myself
>>> into the __new__ method of the Base class.
>>>
>>> Thanks!
>>>
>>> Pau.
>>>
>>> --
>>> ----------------------------------
>>> Pau Tallada Crespí
>>> Dep. d'Astrofísica i Cosmologia
>>> Port d'Informació Científica (PIC)
>>> Tel: +34 93 586 8233
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>>
>>
>>
>> --
>> ----------------------------------
>> Pau Tallada Crespí
>> Dep. d'Astrofísica i Cosmologia
>> Port d'Informació Científica (PIC)
>> Tel: +34 93 586 8233
>> ----------------------------------
>>
>>
>
>
> --
> ----------------------------------
> Pau Tallada Crespí
> Dep. d'Astrofísica i Cosmologia
> Port d'Informació Científica (PIC)
> Tel: +34 93 586 8233
> ----------------------------------
>
>
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--
----------------------------------
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Dep. d'Astrofísica i Cosmologia
Port d'Informació Científica (PIC)
Tel: +34 93 586 8233
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