> Thanks a lot Mike! This gives me interesting paths to research.
For the record, I finally wrote my own association_proxy. This is an
hybrid between SQLAlchemy's association_proxy and hybrid_property.
class _association_proxy(object):
# A specific "association proxy" implementation
def __init__(self, target, value_attr):
self.target = target
self.value_attr = value_attr
def __get__(self, obj, type=None):
if obj is None:
# For "hybrid" descriptors that work both at the instance
# and class levels we could return an SQL expression here.
# The code of hybrid_property in SQLAlchemy illustrates
# how to do that.
raise AttributeError
return getattr(getattr(obj, self.target), self.value_attr)
def __set__(self, obj, val):
o = getattr(obj, self.target)
# if the obj as no child object or if the child object
# does not correspond to the new value then we need to
# read a new child object from the database
if not o or getattr(o, self.value_attr) != val:
relationship_property = class_mapper(obj.__class__) \
.get_property(self.target)
child_cls = relationship_property.argument
o = Session.query(child_cls).filter(
getattr(child_cls, self.value_attr) == val).first()
setattr(obj, self.target, o)
Thanks again Mike for your support.
--
Eric Lemoine
Camptocamp France SAS
Savoie Technolac, BP 352
73377 Le Bourget du Lac, Cedex
Tel : 00 33 4 79 44 44 96
Mail : [email protected]
http://www.camptocamp.com
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