On Oct 14, 2010, at 9:28 AM, Julien Cigar wrote:
> Given all this "magic" with .with_polymorphic(), I'm now wondering if it's
> really worth to have a new Query class (by subclassing orm.Query) per mapped
> object just to apply some filters...
>
> At first I found quite elegant to have one Query object per mapped class, but
> now I'm wondering if it's not better after all to have a bunch of
> @staticmethod in the model ...
>
> What do you think ?
I generally think subclasses of Query should be used very conservatively, and
that model specific behavior should be in the model, sure.
>
> On 10/13/2010 11:21, Julien Cigar wrote:
>> On 10/12/2010 18:05, Julien Cigar wrote:
>>> On 10/12/2010 17:09, Michael Bayer wrote:
>>>> On Oct 12, 2010, at 7:39 AM, Julien Cigar wrote:
>>>>
>>>>> Hello,
>>>>>
>>>>> any idea why with
>>>>>
>>>>> # Query
>>>>>
>>>>> class BaseQuery(orm.Query):
>>>>> @dynamic
>>>>> def method_a(self):
>>>>> ...
>>>>> def method_b(self):
>>>>> ...
>>>>>
>>>>> class FooQuery(BaseQuery):
>>>>> ...
>>>>>
>>>>> class BarQuery(FooQuery):
>>>>> @dynamic
>>>>> def method_c(self):
>>>>> ...
>>>>>
>>>>> # Models
>>>>>
>>>>> class BaseModel(object):
>>>>> query = Session.query_property(BaseQuery)
>>>>>
>>>>> #
>>>>>
>>>>> myQuery = type('PolymorphicQuery, (content.BaseQuery, ),
>>>>> func_list)(BaseModel)
>>>>>
>>>>> where "func_list" containing all the functions decorated by @dynamic
>>>>> the following fail? :
>>>>>
>>>>> - myQuery.get(45) fails with: AttributeError: 'NoneType' object has
>>>>> no attribute 'identity_map'
>>>>> - myQuery.method_a().all() fails with: AttributeError: 'NoneType'
>>>>> object has no attribute '_autoflush'
>>>>> - etc
>>>>>
>>
>> OK I think I found a solution, I need to pass session=Session.registry()
>> to my custom query:
>>
>> >>> model.content.ContentQuery.__mro__
>> (<class 'amnesia.model.content.ContentQuery'>, <class
>> 'amnesia.model.root.RootQuery'>, <class 'sqlalchemy.orm.query.Query'>,
>> <type 'object'>)
>> >>> PolymorphicQuery = type('PolymorphicQuery',
>> (model.content.ContentQuery, ), {})
>> >>> q1 = PolymorphicQuery(model.Content)
>> >>> q1.get(25)
>> Traceback (most recent call last):
>> File "<console>", line 1, in <module>
>> File
>> "/home/jcigar/venvs/pylons0.9.7/lib/python2.5/site-packages/SQLAlchemy-0.6.4-py2.5.egg/sqlalchemy/orm/query.py",
>> line 595, in get
>> return self._get(key, ident)
>> File
>> "/home/jcigar/venvs/pylons0.9.7/lib/python2.5/site-packages/SQLAlchemy-0.6.4-py2.5.egg/sqlalchemy/orm/query.py",
>> line 1803, in _get
>> instance = self.session.identity_map.get(key)
>> AttributeError: 'NoneType' object has no attribute 'identity_map'
>> >>> q2 = PolymorphicQuery(model.Content, session=meta.Session.registry())
>> >>> q2.get(25)
>> <amnesia.model.event.Event object at 0x939046c>
>>
>> I hope I'm not doing something wrong :p
>>
>>>>> My goal is to be able to build a custom Query object to use with the
>>>>> .with_polymorphic() function ..
>>>> I've just grepped through all the source, examples and tests plus the
>>>> wiki trying to find what @dynamic is. Seems like something I'd have
>>>> come up with in the past but I've no clue at the moment what that is.
>>>>
>>>>
>>>
>>> Sorry, I forgot to mention that it's just a custom decorator of mine
>>> which add the function name to a list ... forget about it, it's just to
>>> build the third argument of type() (func_list in my case)
>>>
>>
>
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> <jcigar.vcf>
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