form.changed_data breaks on invalid intial data.

[Florian Apolloner]

Traceback from the admin after the following steps (came up in IRC today):

• Open ​http://localhost:8000/admin/auth/user/1/
• Change "date joined" to an invalid date
• Hit "save and continue editing" -- a normal form error is shown
• Change the date back to a valid value and hit save
• Get greeted by the following traceback:

  Environment:
  
  
  Request Method: POST
  Request URL: http://localhost:8000/admin/auth/user/1/
  
  Django Version: 1.8.dev20141015153619
  Python Version: 2.7.8
  Installed Applications:
  ('django.contrib.admin',
   'django.contrib.auth',
   'django.contrib.contenttypes',
   'django.contrib.sessions',
   'django.contrib.messages',
   'django.contrib.staticfiles')
  Installed Middleware:
  ('django.contrib.sessions.middleware.SessionMiddleware',
   'django.middleware.common.CommonMiddleware',
   'django.middleware.csrf.CsrfViewMiddleware',
   'django.contrib.auth.middleware.AuthenticationMiddleware',
   'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
   'django.contrib.messages.middleware.MessageMiddleware',
   'django.middleware.clickjacking.XFrameOptionsMiddleware',
   'django.middleware.security.SecurityMiddleware')
  
  
  Traceback:
  File "/home/florian/sources/django.git/django/core/handlers/base.py" in get_response
    125.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/florian/sources/django.git/django/contrib/admin/options.py" in wrapper
    602.                 return self.admin_site.admin_view(view)(*args, **kwargs)
  File "/home/florian/sources/django.git/django/utils/decorators.py" in _wrapped_view
    110.                     response = view_func(request, *args, **kwargs)
  File "/home/florian/sources/django.git/django/views/decorators/cache.py" in _wrapped_view_func
    54.         response = view_func(request, *args, **kwargs)
  File "/home/florian/sources/django.git/django/contrib/admin/sites.py" in inner
    212.             return view(request, *args, **kwargs)
  File "/home/florian/sources/django.git/django/contrib/admin/options.py" in change_view
    1477.         return self.changeform_view(request, object_id, form_url, extra_context)
  File "/home/florian/sources/django.git/django/utils/decorators.py" in _wrapper
    34.             return bound_func(*args, **kwargs)
  File "/home/florian/sources/django.git/django/utils/decorators.py" in _wrapped_view
    110.                     response = view_func(request, *args, **kwargs)
  File "/home/florian/sources/django.git/django/utils/decorators.py" in bound_func
    30.                 return func.__get__(self, type(self))(*args2, **kwargs2)
  File "/home/florian/sources/django.git/django/utils/decorators.py" in inner
    145.                     return func(*args, **kwargs)
  File "/home/florian/sources/django.git/django/contrib/admin/options.py" in changeform_view
    1431.                     change_message = self.construct_change_message(request, form, formsets)
  File "/home/florian/sources/django.git/django/contrib/admin/options.py" in construct_change_message
    1006.         if form.changed_data:
  File "/home/florian/sources/django.git/django/forms/forms.py" in changed_data
    462.                 if field.has_changed(initial_value, data_value):
  File "/home/florian/sources/django.git/django/forms/fields.py" in has_changed
    1104.             if field.has_changed(field.to_python(initial), data):
  File "/home/florian/sources/django.git/django/forms/fields.py" in to_python
    483.         return super(TimeField, self).to_python(value)
  File "/home/florian/sources/django.git/django/forms/fields.py" in to_python
    437.         raise ValidationError(self.error_messages['invalid'], code='invalid')
  
  Exception Type: ValidationError at /admin/auth/user/1/
  Exception Value: [u'Enter a valid time.']
  
  

[Baptiste Mispelon]

Interestingly, there is no error when you do the same procedure with the "last login" field.

[Grzegorz Ślusarek]

here is the pr: ​https://github.com/django/django/pull/3703

[Florian Apolloner]

Commented on the PR

[Grzegorz Ślusarek]

here is improved pr:
​https://github.com/django/django/pull/3708

[Tim Graham]

Not sure if this is a regression, but since it's a crashing issue, we can probably add release notes and backport to 1.7.

[Tim Graham <timograham@…>]

In 0dea81cd6d34b3e41cc4bbec99b5fdf06142b09e:

Fixed #23674 -- Fixed a crash when a MultiValueField has invalid data.

[Tim Graham <timograham@…>]

In 4b96e862b4674e85d1a28f2849685aa3135bc557:

[1.7.x] Fixed #23674 -- Fixed a crash when a MultiValueField has invalid data.

Backport of 0dea81cd6d34b3e41cc4bbec99b5fdf06142b09e from master