Ticket #10728: 0001-Allow-subclassing-field-types-that-use-the-SubfieldB.patch

django/db/models/fields/subclassing.py

@@ -79 +79 @@
     def __new__(cls, base, name, attrs):
         new_class = super(SubfieldBase, cls).__new__(cls, base, name, attrs)
         new_class.contribute_to_class = make_contrib(
-                attrs.get('contribute_to_class'))
+                attrs.get('contribute_to_class'), new_class)
         return new_class
 
 class Creator(object):
@@ -97 +97 @@
     def __set__(self, obj, value):
         obj.__dict__[self.field.name] = self.field.to_python(value)
 
-def make_contrib(func=None):
+def make_contrib(func, field_class):
     """
     Returns a suitable contribute_to_class() method for the Field subclass.
 
@@ -110 +110 @@
         if func:
             func(self, cls, name)
         else:
-            super(self.__class__, self).contribute_to_class(cls, name)
+            super(field_class, self).contribute_to_class(cls, name)
         setattr(cls, self.name, Creator(self))
 
     return contribute_to_class

tests/modeltests/field_subclassing/models.py

@@ -53 +53 @@
             return []
         raise FieldError('Invalid lookup type: %r' % lookup_type)
 
+class OtherField(SmallField):
+    """
+    Check the SubfieldBase metaclass works with inheritance.
+    """
+
+    pass
+
+def make_othermodel():
+    """
+    Isolate OtherModel class definition.
+
+    When the test fails, it fails at class definition with a long
+    stack trace. This confuses test discovery, so wrap it in a function.
+    """
+
+    try:
+        class OtherModel(models.Model):
+            other_data = OtherField(default='example')
+    except RuntimeError: # Maximum recursion depth
+        raise RuntimeError("Couldn't subclass field")
+    else:
+        return OtherModel
+
 class MyModel(models.Model):
     name = models.CharField(max_length=10)
     data = SmallField('small field')
@@ -102 +125 @@
 >>> obj.object == m
 True
 
+# Test custom field subclassing.
+>>> OtherModel = make_othermodel()
+>>> om = OtherModel()
+>>> om.other_data = 'plop'
+>>> str(om.other_data)
+"pl"
+
 # Test retrieving custom field data
 >>> m.delete()
 >>> m1 = MyModel(name="1", data=Small(1, 2))