InstrumentedList/InstrumentedAttribute to dynamic query

[Ahmed]

Hello,
I wonder if there is a possibility given an object instance (say with
an InstrumentedList of a relationship attribute).. to get a
corresponding dynamic query of this same InstrumentedList (the List
was configured in the declarative class with a lazy loader and not a
dynamic loader)??

Cheers

[Ahmed]

It seems I am very close to an answer by Michael Bayer demonstrated in
that thread:
http://groups.google.com/group/sqlalchemy/browse_thread/thread/2f60ee62e1ed6a0a

I changed the strategies on the class mapper RelationshipProperties as
follows:

def make_dynamic(sqlalchemy_class):
mapper = class_mapper(sqlalchemy_class)

for prop in mapper.iterate_properties:
if isinstance(prop, RelationshipProperty):
prop.strategy_class = strategies.factory('dynamic')
interfaces.StrategizedProperty.do_init(prop)

changing the strategy to subquery seems to be working fine (sql
queries run in console on instance loading), however changing that to
'dynamic' does not get the same effect and I still have normal
instrumented lists instead of appender queries.

Any clues? I appreciate your help.

Cheers,
Ahmed

[Michael Bayer]

On Aug 24, 2011, at 11:12 PM, Ahmed wrote:

> It seems I am very close to an answer by Michael Bayer demonstrated in
> that thread:
> http://groups.google.com/group/sqlalchemy/browse_thread/thread/2f60ee62e1ed6a0a
>
> I changed the strategies on the class mapper RelationshipProperties as
> follows:
>
> def make_dynamic(sqlalchemy_class):
> mapper = class_mapper(sqlalchemy_class)
>
> for prop in mapper.iterate_properties:
> if isinstance(prop, RelationshipProperty):
> prop.strategy_class = strategies.factory('dynamic')
> interfaces.StrategizedProperty.do_init(prop)
>
> changing the strategy to subquery seems to be working fine (sql
> queries run in console on instance loading), however changing that to
> 'dynamic' does not get the same effect and I still have normal
> instrumented lists instead of appender queries.
>
> Any clues? I appreciate your help.

from the original question it appears you're looking to do a with_parent kind of query... if you have MyClass->MyRelated ...

class MyClass(Base):
...

stuff = relationship("MyRelated")

@property
def dynamic_stuff(self):
return object_session(self).query(MyRelated).with_parent(self, "stuff")

no tinkering with internals needed in that case...

>
> Cheers,
> Ahmed
>
>
> On Aug 22, 5:04 pm, Ahmed <ahmedba...@gmail.com> wrote:
>> Hello,
>> I wonder if there is a possibility given an object instance (say with
>> an InstrumentedList of a relationship attribute).. to get a
>> corresponding dynamic query of this same InstrumentedList (the List
>> was configured in the declarative class with a lazy loader and not a
>> dynamic loader)??
>>
>> Cheers
>

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