[sqlalchemy] Re: Polymorphic collections / ticket #500

2007-03-12 Thread Rick Morrison
Yeah, disregard this, I found an easier way that doesn't fight SA. For the record, the use case is a polymorphic collection with the occasional exception. Exceptions were one-offs for which I didn't want to provide derived mappers because they were well, rare one-offs. Those exceptions were to be

[sqlalchemy] Re: Polymorphic collections / ticket #500

2007-03-07 Thread Michael Bayer
im not sure if i understand the use case youre describing ? I also stuck the previously mentioned flag in the trunk, the exception message will tell you about it. On Mar 6, 2007, at 11:08 PM, Rick Morrison wrote: Mike: I think I've seen a few requests here on the list over the past

[sqlalchemy] Re: Polymorphic collections / ticket #500

2007-03-06 Thread King Simon-NFHD78
I wanted to do something like this in the past, and in the end, rather than using polymorphic mappers it made more sense to create a MapperExtension which overrides create_instance. In create_instance you can examine your 'typ' column to decide what class to create, selecting one of your