newforms-admin: Changed Widget._has_changed to *only* use an empty string when data and/or initial is None. False values were tripping up the conditional.

git-svn-id: http://code.djangoproject.com/svn/django/branches/newforms-admin@7366 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/newforms/forms.py

@@ -254,7 +254,6 @@ class BaseForm(StrAndUnicode):
             data_value = field.widget.value_from_datadict(self.data, self.files, prefixed_name)
             initial_value = self.initial.get(name, field.initial)
             if field.widget._has_changed(initial_value, data_value):
-                #print field
                 return True
         return False
 

django/newforms/widgets.py

@@ -172,8 +172,14 @@ class Widget(object):
         # For purposes of seeing whether something has changed, None is
         # the same as an empty string, if the data or inital value we get
         # is None, replace it w/ u''.
-        data_value = data or u''
+        if data is None:
-        initial_value = initial or u''
+            data_value = u''
+        else:
+            data_value = data
+        if initial is None:
+            initial_value = u''
+        else:
+            initial_value = initial
         if force_unicode(initial_value) != force_unicode(data_value):
             return True
         return False

tests/regressiontests/forms/forms.py

@@ -1717,4 +1717,25 @@ Traceback (most recent call last):
 ...
 AttributeError: 'SongForm' object has no attribute 'cleaned_data'
 
+If a field is not given in the data then None is returned for its data. Lets
+make sure that when checking for empty_permitted that None is treated
+accordingly.
+
+>>> data = {'artist': None, 'song': ''}
+>>> form = SongForm(data, empty_permitted=True)
+>>> form.is_valid()
+True
+
+However, we *really* need to be sure we are checking for None as any data in
+initial that returns False on a boolean call needs to be treated literally.
+
+>>> class PriceForm(Form):
+...     amount = FloatField()
+...     qty = IntegerField()
+
+>>> data = {'amount': '0.0', 'qty': ''}
+>>> form = PriceForm(data, initial={'amount': 0.0}, empty_permitted=True)
+>>> form.is_valid()
+True
+
 """