Cannot specify form_class that isn't subclass of TypedChoiceField for field with choices
|Reported by:||carljm||Owned by:||nobody|
|Cc:||Triage Stage:||Ready for checkin|
|Has patch:||yes||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
In Field.formfield(), if self.choices is set, Django overrides any supplied form_class with TypedChoiceField unless the given form_class is a subclass of TypedChoiceField. This is unnecessarily restrictive (as explicit type checks usually are), and is particularly problematic when working with a field that takes multiple values (such as a Postgres array field), where TypedMultipleChoiceField would be the appropriate form field class, because TypedMultipleChoiceField is not a subclass of TypedChoiceField.
Prior to the fix for #18162, Django was even more restrictive; a custom form_class was not respected at all when choices were set.
I think the wrong fix for #18162 was chosen. The original patch provided by rafallo there would have respected a new keyword argument to formfield(), form_class_for_choices. This provides full flexibility, and is conceptually more correct; since a totally different form field is generally needed for the same db field when there are choices, a separate keyword argument to control this form field is appropriate. I propose that we switch to rafallo's fix (though I prefer the slightly shorter name choices_form_class).
Unfortunately since the subclass check was committed and released in the 1.6 betas, we probably still have to maintain compatibility with people passing a subclass of TypedChoiceField as form_class and expecting it to be used when choices are set.
Change History (8)
comment:2 Changed 6 months ago by mjtamlyn
- Triage Stage changed from Unreviewed to Ready for checkin
comment:7 Changed 6 months ago by Carl Meyer <carl@…>
- Resolution set to fixed
- Status changed from new to closed