id summary reporter owner description type status component version severity resolution keywords cc stage has_patch needs_docs needs_tests needs_better_patch easy ui_ux
16612 Localized form fields cause Form.has_changed() to always return True. rviotti@… nobody "Localized form fields are causing Form.has_changed() to always return True.
I've created a minimal project to test this. Here is the relevant part of the settings.py file.
{{{
TIME_ZONE = 'America/Sao_Paulo'
USE_THOUSAND_SEPARATOR = True
LANGUAGE_CODE = 'pt-br'
USE_I18N = True
USE_L10N = True
}}}
The test model.
{{{
from django.db import models
class TestModel(models.Model):
numeric_field = models.DecimalField(max_digits=10, decimal_places=2)
@models.permalink
def get_absolute_url(self):
return ('edit', [str(self.pk)])
}}}
The test form.
{{{
from django import forms
from app.models import TestModel
class TestForm(forms.ModelForm):
class Meta:
model = TestModel
numeric_field = forms.DecimalField(localize=True)
}}}
The test view.
{{{
from django.shortcuts import get_object_or_404, render, redirect
from app.forms import TestForm
from app.models import TestModel
def edit_instance(request, instance_id):
inst = get_object_or_404(TestModel, pk=instance_id)
if request.method == 'POST':
form = TestForm(request.POST, instance=inst)
if form.is_valid():
inst = form.save()
print 'FORM CHANGED?', form.has_changed()
return redirect(inst)
else:
form = TestForm(instance=inst)
return render(request, 'testmodel.html', {'form': form})
}}}
And template code.
{{{
Bugreports
}}}
The print statement above emits True whenever I hit the submit button, regardless of changes on the numeric field value. This is because Form._has_changed_data is comparing raw localized POST data with initial data, coming from the model, both converted to Unicode. For example, the request POST data is ""1,23"" and the initial data obtained from the model field is Decimal('1.23'). The test ""unicode(u'1,23') == unicode(Decimal('1.23'))"" fails.
The following !ModelForm specialization compares initial data with cleaned data, which, IMHO, is the adequate way to do field change detection.
{{{
class ModelFormSubclass(forms.ModelForm):
def _get_changed_data(self):
if self._changed_data is None:
self._changed_data = []
for name, field in self.fields.items():
data_value = self.cleaned_data[name]
initial_value = self.initial.get(name, field.initial)
# Replace instances with their primary key values.
if hasattr(data_value, 'pk'):
data_value = data_value.pk
if data_value != initial_value:
self._changed_data.append(name)
return self._changed_data
changed_data = property(_get_changed_data)
}}}
The overriden method fixed my specific problem. I'm posting it primarily for consideration of the proposed concept, and secondly, as a preliminary solution to the aforementioned issue.
" Bug closed Forms dev Normal fixed Ready for checkin 1 0 0 0 0 0