[Django] #35979: Empty form ErrorList display as square brackets "[]"

[Django]

#35979: Empty form ErrorList display as square brackets "[]"
-------------------------------------+-------------------------------------
Reporter: Benjamin Mampaey | Type:
| Uncategorized
Status: new | Component: Forms
Version: 5.1 | Severity: Normal
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 1
-------------------------------------+-------------------------------------
This is probably not a Django bug, it does not appear when running Django
with manage.py runserver, but appears when running django with apache2 and
some versions of mod_wsgi. I believe it should be made public so that if
other people stumble on that problem, they know how to fix it.

In the admin templates, when forms are displayed, if there are no errors,
there is a pair of square brackets above the label. For example in the
login form, it shows a pair of square brackets above the label "Username".

From what I could find, mod_wsgi uses sub interpreters, and in version
below 2.12.5 there is a bug where the MRO for !__str!__ is not properly
done https://mliezun.github.io/2024/08/19/cpython-subinterpreters.html.

In the admin template, form errors are displayed using the !__str!__
method, for example in the login template, for the Username field :

{{{
<div class="form-row">
{{ form.username.errors }}
{{ form.username.label_tag }} {{ form.username }}
</div>
}}}

And the definition of ErrorList is

{{{
class ErrorList(UserList, list, RenderableErrorMixin)
}}}

Thus, because of the bug, when calling the !__str!__ method of ErrorList,
instead of calling the !__str!__ method of RenderableErrorMixin, that
returns an empty string '', it is the !__str!__ method of list that is
called that returns '[]'.
--
Ticket URL: <https://code.djangoproject.com/ticket/35979>
Django <https://code.djangoproject.com/>
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[Django]

#35979: Empty form ErrorList display as square brackets "[]"

----------------------------------+--------------------------------------
Reporter: Benjamin Mampaey | Owner: (none)
Type: Uncategorized | Status: closed
Component: Forms | Version: 5.1
Severity: Normal | Resolution: invalid

Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 1

----------------------------------+--------------------------------------
Changes (by Sarah Boyce):

* resolution: => invalid
* status: new => closed

Comment:

Thank you Benjamin, this ticket will keep a record

Since the goal of this issue tracker is to track issues about Django
itself, I'll be closing this ticket as invalid following the
[https://docs.djangoproject.com/en/dev/internals/contributing/triaging-
tickets/#closing-tickets ticket triaging process].
If, after debugging, you find out that this is a bug in Django, please re-
open with the specific details and please be sure to include a small
Django project to reproduce or a failing test case.
--
Ticket URL: <https://code.djangoproject.com/ticket/35979#comment:1>

[Django]

#35979: Empty form ErrorList display as square brackets "[]"
----------------------------------+--------------------------------------
Reporter: Benjamin Mampaey | Owner: (none)
Type: Uncategorized | Status: closed
Component: Forms | Version: 5.1
Severity: Normal | Resolution: invalid
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 1
----------------------------------+--------------------------------------

Comment (by Bob Kline):

Until that bug gets fixed, I found that adding


{{{
WSGIApplicationGroup %{GLOBAL}
}}}


to the block for the virtual host works around the problem.
--
Ticket URL: <https://code.djangoproject.com/ticket/35979#comment:2>