Opened 4 months ago

Closed 4 months ago

Last modified 4 months ago

#33040 closed Uncategorized (invalid)

BaseModelForm.is_valid() should document how it modifies the BaseModelForm.instance

Reported by: Danang Rahmatullah Owned by: nobody
Component: Documentation Version: 3.2
Severity: Normal Keywords: BaseModelForm is_valid
Cc: Triage Stage: Unreviewed
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description

BasedModelForm extends BaseForm. When BaseModelForm().is_valid() is called, its super is called which in turn calls BaseForm.errors (property method). The issue is when there are no errors (self._errors is None): BaseForm calls full_clean() which runs the _post_clean() hook defined in BaseModelForm, finally modifying BaseModelForm.instance.

Given the abstraction level of subclasses of BaseModelForm such as forms.ModelForm, it is very unreasonable to expect that a seemingly simple function like is_valid() to create such a big change to a property as important as instance. I hope this side-effect is clearly explained in the documentation or have the code refactored to separate the modifying effect of is_valid() function from the form validity check

# form.instance.myfield = False
form = MyModelForm(instance=myinstance, data={"myfield": True})
# form.instance.myfield = False
form.is_valid()
# form.instance.myfield = True

Change History (2)

comment:1 Changed 4 months ago by Mariusz Felisiak

Easy pickings: unset
Resolution: invalid
Status: newclosed

I hope this side-effect is clearly explained in the documentation or have the code refactored to separate the modifying effect of is_valid() function from the form validity check

Yes, this is explained in detail in docs. I'm not sure what change you're proposing.

If you're having trouble understanding how Django works, see TicketClosingReasons/UseSupportChannels for ways to get help.

comment:2 Changed 4 months ago by Danang Rahmatullah

Thanks for the link attached. I was mainly looking at the Forms API page which currently has no references to the link you have posted. In that case, I think adding a small reference link to the validation page from the forms API page would greatly help others.

Note: See TracTickets for help on using tickets.
Back to Top