On Dec 29, 2012, at 3:03 AM, Gerald Thibault wrote:
> I'll post a test case later if needed, but this is more of a technical
> question so i don't think it will be needed.
>
> When i use iterate_properties on a class with a hybrid_property, it's not
> shown in the list. I am trying to 'extract' fields from classes in order to
> automatically build forms from them. iterate_properties was useful for
> getting most info, but eventually i had to start using 'for k in dir(class)'
> to get access to association proxies on the classes. I would use getattr(cls,
> k) to get the object, but for hybrid properties this calls fget, and directly
> returns a BinaryExpression, rather than the property itself. The only way I
> can find to access the actual hybrid_property object is via vars(cls), and
> then, this doesn't contain hybrid properties defined on the bases which are
> being used by the class.
>
> Is there a way built into sqlalchemy to get all hybrid_property objects for a
> class, both those declared on the active class and those declared on the base
> classes? I'm mainly interested in determining whether a setter has been
> provided on the property, to determine if it's readonly or not.
There's no API system of reading non-MapperProperty objects, which includes all
the various descriptors we have in sqlalchemy.ext. It might be nice to add
such an API to do so and make this an extension of the 0.8 inspect() system,
but anyway for now when you read class-bound descriptors like this, you have to
work around the fact that they have classbound behavior, which means you can't
use getattr().
An iterative approach which uses __dict__ to get at everything might be like
this (not tested):
def all_attrs(cls):
keys = set()
for supercls in cls.__mro__:
for k in supercls.__dict__.difference(keys):
keys.add(k)
v = supercls.__dict__[k]
if isinstance(v, (InstrumentedAttribute, AssociationProxy,
hybrid_property):
yield v
>
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