Ticket #4485: decimal_field_nullable_r7722.diff

django/db/models/fields/__init__.py

@@ -689 +689 @@
                 _("This value must be a decimal number."))
 
     def _format(self, value):
-        if isinstance(value, basestring):
+        if isinstance(value, basestring) or value is None:
             return value
         else:
             return self.format_number(value)

tests/regressiontests/model_fields/tests.py

@@ -15 +15 @@
 Traceback (most recent call last):
 ...
 ValidationError: [u'This value must be a decimal number.']
+
+>>> f = DecimalField(max_digits=5, decimal_places=1)
+
+>>> f.get_db_prep_save(2.0) 
+u'2.0'
+
+>>> f.get_db_prep_save(2.56) 
+u'2.6'
+
+>>> f.get_db_prep_save(None) 
+>>> f.get_db_prep_lookup('exact', 2.0) 
+[u'2.0']
+
+>>> f.get_db_prep_lookup('exact', 2.56) 
+[u'2.6']
+
+>>> f.get_db_prep_lookup('exact', None) 
+[None]
+
 """