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Migrated issue, originally created by Markus Meskanen (@Mahi)
As it stands, if you want to override super class's hybrid_decorator's getter, you end up having to re-write the whole decorator, since there's no getter() method.
For example, you can't do this:
class Foo(Model):
first_name = Column(String)
@hybrid_property
def name(self):
return self.first_name
class Bar(Foo):
last_name = Column(String)
@Foo.name.getter
def name(self):
return self.first_name + ' ' + self.last_name
In the example above it doesn't matter since there's only getter, but if we had setter, expression, and deleter defined, we would have to manually copy them over to Bar since we have to create a new hybrid_property instead of calling .getter on the super class.
Python's built-in property also supports this, for what it's worth:
>>> class Foo:
... _x = 0
... @property
... def x(self):
... return self._x
... @x.setter
... def x(self, value):
... self._x = value
...
>>> class Bar(Foo):
... @Foo.x.getter
... def x(self):
... return self._x - 1
...
>>> b = Bar()
>>> b._x
0
>>> b.x
-1
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sqlalchemy-bot commentedon Feb 13, 2017
Changes by Markus Meskanen (@Mahi):
sqlalchemy-bot commentedon Feb 13, 2017
Michael Bayer (@zzzeek) wrote:
this is fair and would be bundled with #3912 as an enhancement package. targeting for 1.2 but this may move out unless I can get contributions including tests.
sqlalchemy-bot commentedon Feb 13, 2017
Changes by Michael Bayer (@zzzeek):
sqlalchemy-bot commentedon Mar 16, 2017
diana clarke wrote:
Hmmm... perhaps I just haven't had enough coffee yet, but this isn't working the way I would have expected (differs from the python behaviour).
Compare the output from Person/LoudPerson with PythonPerson/PythonLoudPerson, where the classes prefixed with "Python" are just plain old python classes and the others are sqlalchemy models.
sqlalchemy-bot commentedon Mar 16, 2017
Michael Bayer (@zzzeek) wrote:
ok.... this is overriding setter, is this after patching like in #3912 ? the hybrid doesn't yet copy itself the way @Property does.
sqlalchemy-bot commentedon Mar 16, 2017
diana clarke wrote:
Ah, I had wondered after I posted that question, if I should start with #3912 instead (I didn't really read that one deeply). I'll do that. Thanks!
sqlalchemy-bot commentedon Mar 16, 2017
diana clarke wrote:
Yup, shamelessly stealing these [1] from Hettinger fixed it :)
[1] https://github.com/python/cpython/blob/master/Doc/howto/descriptor.rst#properties
sqlalchemy-bot commentedon Mar 16, 2017
diana clarke wrote:
The above approach isn't going to work if you want to override more than one of setter/getter/deleter, but then again it doesn't work in the plain old python case either. My batting average isn't great this week ;)
sqlalchemy-bot commentedon Mar 21, 2017
Michael Bayer (@zzzeek) wrote:
Allow reuse of hybrid_property across subclasses
The :class:
sqlalchemy.ext.hybrid.hybrid_propertyclass now supportscalling mutators like
@setter,@expressionetc. multiple timesacross subclasses, and now provides a
@gettermutator, so thata particular hybrid can be repurposed across subclasses or other
classes. This now matches the behavior of
@propertyin standardPython.
Co-authored-by: Mike Bayer mike_mp@zzzcomputing.com
Fixes: #3911
Fixes: #3912
Change-Id: Iff033d8ccaae20ded9289cbfa789c376759381f5
→ caeb274
sqlalchemy-bot commentedon Mar 21, 2017
Changes by Michael Bayer (@zzzeek):
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