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Re: SqlAlchemy Adapter

by Nikos Papagrigoriou :: Rate this Message:

I lately found that in order to get the mapper it is better to call:

mapper = sqlalchemy.orm.util.object_mapper(obj, False)

and check if mapper is None.

The documentation says:
def object_mapper(object, raiseerror=True):
"""Given an object, return the primary Mapper associated with the
object instance.

object
The object instance.

raiseerror
Defaults to True: raise an ``InvalidRequestError`` if no
mapper can
be located. If False, return None.

"""

On Sep 22, 2008, at 12:24 AM, dthompso@... wrote:

> Thanks for the suggestion. I used your code, but I ran into problems
> with custom
> collections (classes that are decorated with
> @sqlalchemy.collection.iterator,
> etc.) because they don't have a class manager. I added a simple
> check that uses

Could you please post an example?

>
> the mapper if the object has a class manager, or the __dict__ if it
> doesn't.
> Seems to work with my setup (SA 0.5).
>
> Thanks
> -Dave
>
>
> Quoting nikos@...:
>
>> Hi Dave,
>>
>> I had to make slight changes to your version of SQLAlchemy adapter to
>> return the correct results for my project. The patch is:
>>
>> ----------->8------------- _sqlalchemy.patch --------------
>> >8---------------
>> --- /home/papagr/_sqlalchemy_old.py 2008-09-18 17:29:06.000000000
>> +0200
>> +++ /home/papagr/_sqlalchemy_new.py 2008-09-18 17:29:20.000000000
>> +0200
>> @@ -17,14 +17,15 @@
>> return pyamf.util.native_get_attrs(obj)
>>
>> attrs = {}
>> - for property in obj.__dict__:
>> - if property in sa_properties:
>> + mapper = obj._sa_class_manager.mapper
>> + for property in mapper.iterate_properties:
>> + if property.key in sa_properties:
>> continue
>>
>> - if property.startswith('__'):
>> + if property.key.startswith('__'):
>> continue
>>
>> - attrs[property] = getattr(obj, property)
>> + attrs[property.key] = getattr(obj, property.key)
>> return attrs
>>
>> def write_SA_collection(obj):
>> ----------->8------------- _sqlalchemy.patch --------------
>> >8---------------
>>
>> The reason for using object's mapper to iterate properties instead of
>> fetching object's __dict__ is because SQLAlchemy initially creates
>> _CompileOnAttr except if you manually call mapper's compile method.
>>
>> Expecting your comments,
>>
>> Cheers,
>>
>> Nikos.
>
>
>

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