using a class there which replaces itself means you've developed a custom
creational pattern. A less hacky approach would be to subclass
DeclarativeMeta, and just pass it to your Base:
from sqlalchemy.ext.declarative import DeclarativeMeta
class TefnetMeta(DeclarativeMeta):
def __init__(cls, classname, bases, dict_):
for key, value in dict_.items():
if isinstance(value, TefProperty):
dict_[key] = value._config(cls, key)
super(TefnetMeta, cls).__init__(classname, bases, dict_)
Base = declarative_base(metaclass=TefnetMeta)
On Sep 21, 2012, at 10:17 AM, Tefnet Developers wrote:
> My example is just the shortest code I could come up with to show a problem,
> but in production it doesn't look like this.
> We're using class inheritance, metaclass features etc, so changing it to
> function is not an option for us :|
>
>
> W dniu 21.09.2012 15:59, Michael Bayer pisze:
>> my immediate thought on that code is to replace TefProperty with a function,
>> since you are discarding TefProperty in any case:
>>
>>
>> def propInt():
>> return sa.Column(key, Integer)
>>
>> not sure how the previous Extension version of the code did this
>> differently, this is really a class creational pattern.
>>
>>
>>
>> On Sep 21, 2012, at 2:59 AM, Tefnet Developers wrote:
>>
>>> Hi,
>>> we are trying to migrate our old *Extension based SQLA code to new - event
>>> based.
>>> We also have class based properties that we want to keep. With old SQLA we
>>> have had to monkey-patch _as_declarative function to populate our
>>> properties. I wonder if it is possible to avoid doing it with events? The
>>> only close one we found is "mapper_configured", but I'm afraid it is
>>> executed too late. Anyway... I've prepared some short example code. If you
>>> could take a look and advise if/how it can be done...
>>>
>>> To check out where is the problem change USE_EVENT value from True to False.
>>> https://gist.github.com/3757273
>>>
>>> Regards,
>>> Tomasz Jezierski
>>> Tefnet
>>>
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