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Description
Hello,
In my pynamodb model, I have an attribute, which can be an instance of one of the sub-classes of a polymorphic map attribute like:
class ParentClass(MapAttribute):
cls = DiscriminatorAttribute()
class ChildClass1(ParentClass, discriminator = cls.__name__):
filter_attr = UnicodeAttribute()
class ChildClass2(ParentClass, discriminator = cls.__name__):
other_attr = UnicodeAttribute()
class MyModel(Model):
...
attr = ParentClass()
If I define a filter condition on MyModel.attr.filter_attr like MyModel.attr.filter_attr == value, I get the run time error
def __getattr__(self, attr: str) -> _VT:
# This should only be called for "raw" (i.e. non-subclassed) MapAttribute instances.
# MapAttribute subclasses should access attributes via the Attribute descriptors.
if self.is_raw() and self._is_attribute_container():
try:
return self.attribute_values[attr]
except KeyError:
pass
> raise AttributeError("'{}' has no attribute '{}'".format(self.__class__.__name__, attr))
E AttributeError: 'ParentClass' has no attribute 'filter_attr'
which makes sense because attr is of type ParentClass, which only has cls attribute.
My question is, is there a way to define a filter on a nested attribute in a pynamodb model, where the nested attribute is an instance of a child class of a polymorphic MapAttribute parent class?