#30261: Calling a form method _html_output modifies the self._errors dict for
NON_FIELD_ERRORS if there are hidden field with errors
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Reporter: bmampaey | Owner: nobody
Type: Bug | Status: new
Component: Forms | Version: 2.1
Severity: Normal | Keywords: form errors
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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Each time the _html_output method of a form is called, it appends the
errors of the hidden field errors to the NON_FIELD_ERRORS (__all__) entry.
This happen for example when the form methods as_p() as_table() as_ul()
are called multiple time, or any other method that themselves call one of
them.
For example, a test form with an hidden input field that add errors during
the clean call.
{{{
Python 3.6.5 (default, Apr 25 2018, 14:26:36)
Type 'copyright', 'credits' or 'license' for more information
IPython 6.4.0 -- An enhanced Interactive Python. Type '?' for help.
In [1]: import django
In [2]: django.__version__
Out[2]: '2.1.7'
In [3]: from django import forms
...:
In [4]: class TestForm(forms.Form):
...: hidden_input = forms.CharField(widget=forms.HiddenInput)
...:
...: def clean(self):
...: self.add_error(None, 'Form error')
...: self.add_error('hidden_input', 'Hidden input error')
...:
In [5]: test_form = TestForm({})
In [6]: test_form.errors
Out[6]:
{'hidden_input': ['This field is required.', 'Hidden input error'],
'__all__': ['Form error']}
In [7]: print(test_form.as_table())
<tr><td colspan="2"><ul class="errorlist nonfield"><li>Form
error</li><li>(Hidden field hidden_input) This field is
required.</li><li>(Hidden field hidden_input) Hidden input
error</li></ul><input type="hidden" name="hidden_input"
id="id_hidden_input"></td></tr>
In [8]: test_form.errors
Out[8]:
{'hidden_input': ['This field is required.', 'Hidden input error'],
'__all__': ['Form error', '(Hidden field hidden_input) This field is
required.', '(Hidden field hidden_input) Hidden input error']}
In [9]: print(test_form.as_table())
<tr><td colspan="2"><ul class="errorlist nonfield"><li>Form
error</li><li>(Hidden field hidden_input) This field is
required.</li><li>(Hidden field hidden_input) Hidden input
error</li><li>(Hidden field hidden_input) This field is
required.</li><li>(Hidden field hidden_input) Hidden input
error</li></ul><input type="hidden" name="hidden_input"
id="id_hidden_input"></td></tr>
In [10]: test_form.errors
Out[10]:
{'hidden_input': ['This field is required.', 'Hidden input error'],
'__all__': ['Form error', '(Hidden field hidden_input) This field is
required.', '(Hidden field hidden_input) Hidden input error', '(Hidden
field hidden_input) This field is required.', '(Hidden field hidden_input)
Hidden input error']}
In [11]: test_form.non_field_errors()
Out[11]: ['Form error', '(Hidden field hidden_input) This field is
required.', '(Hidden field hidden_input) Hidden input error', '(Hidden
field hidden_input) This field is required.', '(Hidden field hidden_input)
Hidden input error']
}}}
This bug affects probably also version 2.2.
A simple fix would be to use a copy of the error list before adding the
hidden field errors in the file django/forms/forms.py:
{{{
--- forms.py 2019-03-17 18:59:04.000000000 +0100
+++ forms_fixed.py 2019-03-17 19:00:08.000000000 +0100
@@ -194,7 +194,7 @@
def _html_output(self, normal_row, error_row, row_ender,
help_text_html, errors_on_separate_row):
"Output HTML. Used by as_table(), as_ul(), as_p()."
- top_errors = self.non_field_errors() # Errors that should be
displayed above all fields.
+ top_errors = self.non_field_errors().copy() # Errors that should
be displayed above all fields.
output, hidden_fields = [], []
for name, field in self.fields.items():
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/30261>
Django <https://code.djangoproject.com/>
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