#25408: Pass additional arguments to BaseForm.__init__ from
BaseModelForm.__init__
--------------------------------------+---------------------------------
Reporter: MoritzS | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Forms | Version: master
Severity: Normal | Keywords: form modelform args
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
--------------------------------------+---------------------------------
Consider the following module "myapp.forms":
{{{
class CustomForm(BaseForm):
def __init__(self, **kwargs):
self.custom_kwarg = kwargs.pop('custom_kwarg', 'not available')
def is_valid(self):
if self.custom_kwarg:
return True
else:
return super().is_valid()
class CustomModelForm(ModelForm, CustomForm):
pass
}}}
This module adds additional functionality to forms by adding a new keyword
argument. If you want to use the new feature on a ModelForm too, that
won't work because `BaseModelForm.__init__()` doesn't capture additional
arguments.
You can work around that like follows:
{{{
class CustomFormArg(BaseForm):
def __init__(self, **kwargs):
self.custom_kwarg = kwargs.pop('custom_kwarg', False)
class CustomFormMethod(BaseForm):
def is_valid(self):
if self.custom_kwarg:
return True
else:
return super().is_valid()
class CustomForm(CustomFormArg, CustomFormMethod):
pass
class CustomModelForm(CustomFormArg, ModelForm, CustomFormMethod):
pass
}}}
But I think it makes more sense to let BaseModelForm pass the arguments to
the super() call. Maybe it would also be better if BaseModelForm only took
`**kwargs` instead of listing all arguments again.
Note: In some cases this can be fixed by reversing the bases of
CustomModelForm:
{{{
class CustomModelForm(CustomForm, ModelForm):
pass
}}}
However then the mro would be:
{{{
myapp.forms.CustomModelForm
myapp.forms.CustomForm
django.forms.models.ModelForm
django.forms.models.BaseModelForm
django.forms.forms.BaseForm
object
}}}
instead of the more correct
{{{
myapp.forms.CustomModelForm
django.forms.models.ModelForm
django.forms.models.BaseModelForm
myapp.forms.CustomForm
django.forms.forms.BaseForm
object
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/25408>
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