made SplitField compatible with South FakeORM

model_utils/fields.py

@@ -100,10 +100,19 @@ class SplitDescriptor(object):
             obj.__dict__[self.field.name] = value
 
 class SplitField(models.TextField):
+    def __init__(self, *args, **kwargs):
+        # for South FakeORM compatibility: the frozen version of a
+        # SplitField can't try to add an _excerpt field, because the
+        # _excerpt field itself is frozen as well. See introspection
+        # rules below.
+        self.add_excerpt_field = not kwargs.pop('no_excerpt_field', False)
+        super(SplitField, self).__init__(*args, **kwargs)
+    
     def contribute_to_class(self, cls, name):
-        excerpt_field = models.TextField(editable=False)
-        excerpt_field.creation_counter = self.creation_counter+1
-        cls.add_to_class(_excerpt_field_name(name), excerpt_field)
+        if self.add_excerpt_field:
+            excerpt_field = models.TextField(editable=False)
+            excerpt_field.creation_counter = self.creation_counter+1
+            cls.add_to_class(_excerpt_field_name(name), excerpt_field)
         super(SplitField, self).contribute_to_class(cls, name)
         setattr(cls, self.name, SplitDescriptor(self))
 
@@ -127,7 +136,14 @@ class SplitField(models.TextField):
 # allow South to handle these fields smoothly
 try:
     from south.modelsinspector import add_introspection_rules
-    add_introspection_rules(patterns=['model_utils\.fields\.'])
+    # For a normal MarkupField, the add_excerpt_field attribute is
+    # always True, which means no_excerpt_field arg will always be
+    # True in a frozen MarkupField, which is what we want.
+    add_introspection_rules(rules=[((SplitField,),
+                                    [],
+                                    {'no_excerpt_field': ('add_excerpt_field',
+                                                          {})})],
+                            patterns=['model_utils\.fields\.'])
 except ImportError:
     pass
 

model_utils/tests/models.py

@@ -34,3 +34,11 @@ class Article(models.Model):
 
     def __unicode__(self):
         return self.title
+
+class NoRendered(models.Model):
+    """
+    Test that the no_excerpt_field keyword arg works. This arg should
+    never be used except by the South model-freezing.
+
+    """
+    body = SplitField(no_excerpt_field=True)

model_utils/tests/runtests.py

@@ -13,7 +13,7 @@ from django.conf import settings
 
 def runtests():
     test_runner = get_runner(settings)
-    failures = test_runner([], verbosity=1, interactive=True)
+    failures = test_runner(['tests'], verbosity=1, interactive=True)
     sys.exit(failures)
 
 if __name__ == '__main__':

model_utils/tests/test_settings.py

@@ -9,3 +9,10 @@ INSTALLED_APPS = (
     )
 
 DATABASE_ENGINE = 'sqlite3'
+
+try:
+    import south
+    INSTALLED_APPS += ('south',)
+except ImportError:
+    pass
+

model_utils/tests/tests.py

@@ -1,5 +1,7 @@
 from django.test import TestCase
+from django.conf import settings
 from django.contrib.contenttypes.models import ContentType
+from django.db.models.fields import FieldDoesNotExist
 
 from model_utils import ChoiceEnum
 from model_utils.fields import get_excerpt
@@ -138,3 +140,17 @@ class QueryManagerTests(TestCase):
     def testOrdering(self):
         qs = Post.public_reversed.all()
         self.assertEquals([p.order for p in qs], [5, 4, 1, 0])
+
+if 'south' in settings.INSTALLED_APPS:
+    class SouthFreezingTests(TestCase):
+        def test_introspector_adds_no_excerpt_field(self):
+            from south.modelsinspector import introspector
+            mf = Article._meta.get_field('body')
+            args, kwargs = introspector(mf)
+            self.assertEquals(kwargs['no_excerpt_field'], 'True')
+        
+        def test_no_excerpt_field_works(self):
+            from models import NoRendered
+            self.assertRaises(FieldDoesNotExist,
+                              NoRendered._meta.get_field,
+                              '_body_excerpt')