Stack Overflow Asked by alias51 on November 10, 2021
I have a custom queryset on a model manager:
class TenantManager(models.Manager):
def get_queryset(self):
return super().get_queryset().filter(myfield=myvalue)
class TenantModel(TenantModelMixin, models.Model):
objects = TenantManager()
class Meta:
abstract = True
I use the abstract TenantModel
as a mixin with another model to apply the TenantManager
. E.g.
class MyModel(TenantModel):
This works as expected, applying the TenantManager
filter every time MyModel.objects.all()
is called when inside a view.
However, when I create a ModelForm
with the model, the filter is not applied and all results (without the filter are returned. For example:
class AddPersonForm(forms.ModelForm):
class Meta:
model = MyModel
fields = ('person', )
Why is this and how to I ensure the ModelManager
is applied to the queryset in ModelForm
?
Edit
@Willem suggests the reason is forms use ._base_manager
and not .objects
(although I can not find this in the Django source code), however the docs say not to filter this kind of manager, so how does one filter form queries?
Don’t filter away any results in this type of manager subclass
This
manager is used to access objects that are related to from some other
model. In those situations, Django has to be able to see all the
objects for the model it is fetching, so that anything which is
referred to can be retrieved.If you override the get_queryset() method and filter out any rows,
Django will return incorrect results. Don’t do that. A manager that
filters results in get_queryset() is not appropriate for use as a base
manager.
You can do it in two ways:
First: When creating the form instance, add the queryset for the desired field.
person_form = AddPersonForm()
person_form.fields["myfield"].queryset = TenantModel.objects.filter(myfield="myvalue")
Second: Override the field's queryset in the AddPersonForm
itself.
class AddPersonForm(forms.ModelForm):
class Meta:
model = MyModel
fields = ('person', )
def __init__(self, *args, **kwargs):
super(AddPersonForm, self).__init__(*args, **kwargs)
self.fields['myfield'].queryset = TenantModel.objects.filter(myfield="myvalue")
Answered by jerrymouse on November 10, 2021
I'm not sure why your code doesn't properly works. Probably you haven't reload django app. You could load queryset in __init__
of your form class
class AddPersonForm(forms.ModelForm):
person = forms.ModelMultipleChoiceField(queryset=None)
class Meta:
model = MyOtherModel
fields = ('person', )
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.fields['person'].queryset = MyModel.objects.all()
Answered by Zapix on November 10, 2021
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