Document that ModelMultipleChoiceField queryset may be None
|Reported by:||wraus||Owned by:||nobody|
|Has patch:||yes||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
I have a ModelMultipleChoiceField whose queryset I want to populate after the initialization of the form.
class FooMultipleChoiceForm(forms.Form) foo_select = forms.ModelMultipleChoiceField( label="Foo Selection", help_text="Select a Foo from the choices above.", queryset=None, ) def __init__(self, bar, *args, **kwargs): super(FooMultipleChoiceForm, self).__init__(*args, **kwargs) self.fields['foo_select'].queryset = bar.foo_set.all()
Currently, there are two major issues with this:
- Even if I want to set the queryset later in
self.fields['foo_select'], I still have to specify a queryset attribute when declaring the field, even though the given queryset will be overwritten in
__init__. This not only seems redundant, but it feels odd to be forced to enter a value for the explicit purpose of having it overwritten later, especially when providing None for the queryset attribute doesn't cause any issues if a new queryset is provided in the
__init__of the form.
- If I omit the queryset attribute in ModelMultipleChoiceField, I get a confusing error message:
TypeError: __init__() takes at least 2 arguments (3 given)Nothing is mentioned about the missing queryset argument, and given that I'm setting it later, it's easy to overlook that it's the cause of the problem.
Given that setting queryset to None doesn't cause problems as long as the queryset is initialized later in the form, it seems like it might make sense to allow queryset to be unspecified at field declaration time, as long as it's specified later.
Change History (6)
comment:1 Changed 2 years ago by
|Component:||Forms → Documentation|
|Triage Stage:||Unreviewed → Accepted|
comment:2 Changed 2 years ago by
|Summary:||Improve Error Message / Handling for ModelMultipleChoiceField and queryset attribute → Document that ModelMultipleChoiceField queryset may be None|