id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
21754	"Object discrepency between python2.x and python3.x with model field ""to_python"" and ""get_prep_value"" when retrieving object from database"	Troy Grosfield	nobody	"I put together the following example to demonstrate the differences between python 2 and python 3 and how they handle coercing raw data into model objects when interacting with the db.  Ignore the lame example, it's just to demonstrate the error with python 3.

Current setup:

- python2 test is using python 2.7.6
- python3 test is using python 3.3.3
- Using sqlite backend

{{{
# Model Field and model
class IntStoredAsStringField(models.CharField):
    __metaclass__ = models.SubfieldBase

    def __init__(self, max_length=2000, *args, **kwargs):
        super(IntStoredAsStringField, self).__init__(max_length=max_length,
                                                     *args, **kwargs)

    def to_python(self, value):
        if isinstance(value, int):
            return value

        return int(value)

    def get_prep_value(self, value):
        return smart_text(value)


class SomeModel(models.Model):
    int_stored_as_string_field = IntStoredAsStringField()
}}}

{{{
# test
class Py2To3ErrorTestCase(TestCase):

    def test_show_error(self):
        some_int = 5
        obj = SomeModel(int_stored_as_string_field=some_int)
        obj.save()

        obj_db = SomeModel.objects.get(id=obj.id)
        # field ""to_python"" method gets called when retrieving the object 
        # in python 2, doesn't in python 3 which causes this test to fail
        # in python 3.
        self.assertEqual(obj_db.int_stored_as_string_field,
                         obj.int_stored_as_string_field)
}}}

Test output succeeds in python 2.  In python 3 I see the following error:

{{{

======================================================================
FAIL: test_show_error (Py2To3ErrorTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File ""some/path/test_model_fields.py"", line 150, in test_show_error
    obj.int_stored_as_string_field)
AssertionError: '5' != 5
}}}

The field's ""to_python(...)"" method doesn't get called in python 3 like it does in python 2 when retrieving objects from the db.  Am I missing something here?
"	Bug	closed	Python 3	1.6	Normal	fixed	python3		Unreviewed	0	0	0	0	0	0