python 3 fixes

common/djangoapps/student/models.py

@@ -40,6 +40,7 @@ from django.utils.functional import cached_property
 from django.utils.translation import ugettext_lazy as _
 from django.utils.translation import ugettext_noop
 from django_countries.fields import CountryField
+from django.utils.encoding import python_2_unicode_compatible
 from edx_django_utils.cache import RequestCache
 from edx_rest_api_client.exceptions import SlumberBaseException
 from eventtracking import tracker
@@ -2813,6 +2814,7 @@ class RegistrationCookieConfiguration(ConfigurationModel):
         )
 
 
+@python_2_unicode_compatible
 class UserAttribute(TimeStampedModel):
     """
     Record additional metadata about a user, stored as key/value pairs of text.
@@ -2828,12 +2830,11 @@ class UserAttribute(TimeStampedModel):
     name = models.CharField(max_length=255, help_text=_("Name of this user attribute."), db_index=True)
     value = models.CharField(max_length=255, help_text=_("Value of this user attribute."))
 
-    def __unicode__(self):
-        """Unicode representation of this attribute. """
-        return u"[{username}] {name}: {value}".format(
+    def __str__(self):
+        return "[{username}] {name}: {value}".format(
             name=self.name,
             value=self.value,
-            username=self.user.username,
+            username=self.user.username
         )
 
     @classmethod