Fix #54

sqlalchemy_utils/types/choice.py

@@ -103,7 +103,7 @@ class ChoiceType(types.TypeDecorator, ScalarCoercible):
         return Choice(value, self.choices_dict[value])
 
     def process_bind_param(self, value, dialect):
-        if value:
+        if value and isinstance(value, Choice):
             return value.code
         return value
 

tests/types/test_choice.py

@@ -1,3 +1,4 @@
+from flexmock import flexmock
 from pytest import raises
 import sqlalchemy as sa
 from sqlalchemy_utils import ChoiceType, Choice, ImproperlyConfigured
@@ -36,6 +37,20 @@ class TestChoiceType(TestCase):
         type_ = self.User.__table__.c.type.type
         assert type_.python_type
 
+    def test_string_processing(self):
+        flexmock(ChoiceType).should_receive('_coerce').and_return(
+            u'admin'
+        )
+        user = self.User(
+            type=u'admin'
+        )
+
+        self.session.add(user)
+        self.session.commit()
+
+        user = self.session.query(self.User).first()
+        assert user.type.value == u'Admin'
+
     def test_parameter_processing(self):
         user = self.User(
             type=u'admin'