#16328: FilePathField should include blank option even when required=True
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Reporter: ringemup@… | Owner: nobody
Type: Bug | Status: new
Milestone: | Component: Forms
Version: 1.3 | Severity: Normal
Resolution: | Keywords:
Triage Stage: Accepted | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 1 |
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Changes (by aaugustin):
* easy: 1 => 0
* stage: Unreviewed => Accepted
Comment:
It took me a bit of time to figure out the problem; here's my analysis.
Django's forms have an (undocumented) `empty_permitted` attribute. When
this attribute is set to `True`, validation is short-circuited (see lines
263-266 in django/forms/forms.py). Formsets need this internal API to
display extra forms to add objects, but ignore them if they are submitted
unchanged (empty). Specifically, the inlines feature of the admin uses
this.
However, it isn't possible to submit a formset unchanged when it contains
a `FilePathField`. This problem may affect other fields that can't be
submitted with an empty value, given the UI (radio buttons, drop-down
selects), when `blank=False`. The common point of these fields is that
their value must be chosen from a finite set defined by their `choices`
attribute.
In my opinion, the proper fix is to render fields as if `blank` was `True`
when `empty_permitted` is `True`, probably by setting their
`include_blank` attribute to `True`. Thus, the select widget for
`FilePathField` will contain the blank choice, `BLANK_CHOICE_DASH`, as the
first item, resolving the problem described originally.
Unfortunately, I failed to write a patch for this because I'm not
sufficiently familiar with the forms implementation. After searching for
all instances of `include_blank` and `empty_permitted`, I couldn't bridge
the gap between them. This isn't an easy picking after all :)
--
Ticket URL: <https://code.djangoproject.com/ticket/16328#comment:2>
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