#27037: 'required' attribute on prefilled ClearableFileInput prevents valid form
submissions
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Reporter: gasman | Owner: nobody
Type: Bug | Status: new
Component: Forms | Version: 1.10
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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The addition of the `required` HTML attribute on required form fields
(#22383) does not handle the situation where a `ClearableFileInput` is
pre-populated with an initial value (causing it to display the "Currently:
foo.txt" text alongside an empty `<input type="file">` field) and
submitted without selecting a new file. According to Django's validation
logic this is a valid form submission, as the field is considered non-
empty. However, the browser-side validation doesn't know about this nuance
- at the HTML level, the `<input type="file">` element ''is'' an empty
field, and has the `required` attribute set, causing it to fail
validation.
This breaks the conventional ModelForm-based 'edit' view pattern, on any
model that has a required FileField. For example:
{{{
# models.py
class Document(models.Model):
title = models.CharField(max_length=255)
file = models.FileField()
# forms.py
class DocumentForm(forms.ModelForm):
class Meta:
model = Document
fields = ['title', 'file']
# views.py
def edit(request, document_id):
document = Document.objects.get(id=document_id)
if request.method == 'POST':
# ...
return HttpResponse("OK")
else:
form = DocumentForm(instance=document)
return render(request, 'edit.html', {'document': document, 'form':
form})
# edit.html
<form action="{% url 'edit_document' document.id %}"
method="POST">
{{ form.as_p }}
<input type="submit">
</form>
# renders as the following, which cannot be submitted as-is:
<p><label for="id_file">File:</label> Currently: <a
href="hello.txt">hello.txt</a> <br />Change: <input id="id_file"
name="file" type="file" required /></p>
}}}
I suggest that ClearableFileInput should discard the `required` attribute
whenever an initial value exists, in much the same way that
CheckboxSelectMultiple does:
https://github.com/django/django/blob/35225e2ade08ea32e36a994cd4ff90842c599e20/django/forms/widgets.py#L797-L799
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Ticket URL: <https://code.djangoproject.com/ticket/27037>
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