On Dec 17, 2012, at 12:35 PM, ya...@aknin.name wrote: > Hi, > > SQLAlchemy populates an instance's __dict__ with lazily related instances > when the attributes for these instances are first accessed (see here for an > ancient and huge discussion on the topic; I thought it's better to start > afresh). > > This breaks code that assumes __dict__ encapsulates object state (see here > for a real world example when using flask-restful).
If flask-restful thinks it can get an accurate picture of a Python object's state via __dict__ access alone, it is mistaken. Descriptors are an extremely common system of providing automation behind attribute access, and SQLAlchemy builds upon this standard system. Any serialization system should provide for hooks to customize how the serialization occurs, and assuming flask-restful provides these hooks, that's the solution to take. > > While several workarounds may alleviate this, I think the best approach here > would be to create proxy objects to all relations in any instance's __dict__. > These proxies can be transparently replaced with the real thing upon first > access The Python descriptor already provides a mechanism for proxying data that may or may not be inside of __dict__. It is essential in a system like SQLAlchemy that the structure of __dict__ remain completely simple. Adding another layer of proxying into it would be a massive performance hit and produce tons of bugs where proxy objects don't act like the real thing. flask-restful needs to provide hooks for alternate systems of serialization, plain and simple. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
