#22413: Allow model instance attributes in ModelAdmin.fields
-------------------------------------+-------------------------------------
Reporter: moritzs | Owner: moritzs
Type: New feature | Status: assigned
Component: contrib.admin | Version: master
Severity: Normal | Resolution:
Keywords: ModelAdmin instance | Triage Stage:
attribute field | Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 1 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by moritzs):
Replying to [comment:2 timshaffer@…]:
> Forgive my ignorance (perhaps), but what's wrong with changing your code
to this:
>
> {{{
> class MyModel(models.Model):
> value = models.CharField(max_length=20)
>
> @property
> def reversed_value(self):
> return self.value[::-1]
> }}}
>
> That would not require any changes to Django code.
My example may be a bit trivial, here is another that hopefully shows, why
it is necessary:
{{{
class MyBaseModel(models.Model):
def __getattr__(self, name):
if name.endswith('_to_upper'):
return getattr(self, name[:-len('_to_upper')]).upper()
elif name.endswith('_to_lower'):
return getattr(self, name[:-len('_to_lower')]).lower()
else:
return AttributeError()
class Meta:
abstract = True
class MyModel(MyBaseModel):
val1 = models.CharField(max_length=20)
val2 = models.CharField(max_length=20)
}}}
Now it works like this:
{{{
>>> m = MyModel()
>>> m.val1 = 'Foo'
>>> m.val2 = 'Bar'
>>> m.val1_to_upper
'FOO'
>>> m.val2_to_lower
'bar'
}}}
In this particular example you could still add properties for each
combination of val1, val2 and to_upper, to_lower, but this won't be
possible, if `__getattr__` gets more complex.
--
Ticket URL: <https://code.djangoproject.com/ticket/22413#comment:3>
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