python3 compatibility

cms/djangoapps/contentstore/migrations/0001_initial.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 import django.db.models.deletion
 from django.conf import settings

cms/djangoapps/contentstore/migrations/0002_add_assets_page_flag.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
-from django.db import migrations, models
-from django.conf import settings
 import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
 from opaque_keys.edx.django.models import CourseKeyField
 
 

cms/djangoapps/contentstore/migrations/0003_remove_assets_page_flag.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.db import migrations, models
 

cms/djangoapps/contentstore/signals/handlers.py

 """ receivers of course_published and library_updated events in order to trigger indexing task """
 
+from __future__ import absolute_import
+
+import logging
 from datetime import datetime
 from functools import wraps
-import logging
 
+import six
 from django.core.cache import cache
 from django.dispatch import receiver
 from pytz import UTC
@@ -62,7 +65,7 @@ def listen_for_course_publish(sender, course_key, **kwargs):  # pylint: disable=
         # import here, because signal is registered at startup, but items in tasks are not yet able to be loaded
         from contentstore.tasks import update_search_index
 
-        update_search_index.delay(unicode(course_key), datetime.now(UTC).isoformat())
+        update_search_index.delay(six.text_type(course_key), datetime.now(UTC).isoformat())
 
 
 @receiver(SignalHandler.library_updated)
@@ -75,7 +78,7 @@ def listen_for_library_update(sender, library_key, **kwargs):  # pylint: disable
         # import here, because signal is registered at startup, but items in tasks are not yet able to be loaded
         from contentstore.tasks import update_library_index
 
-        update_library_index.delay(unicode(library_key), datetime.now(UTC).isoformat())
+        update_library_index.delay(six.text_type(library_key), datetime.now(UTC).isoformat())
 
 
 @receiver(SignalHandler.item_deleted)
@@ -113,10 +116,10 @@ def handle_grading_policy_changed(sender, **kwargs):
     Receives signal and kicks off celery task to recalculate grades
     """
     kwargs = {
-        'course_key': unicode(kwargs.get('course_key')),
-        'grading_policy_hash': unicode(kwargs.get('grading_policy_hash')),
-        'event_transaction_id': unicode(get_event_transaction_id()),
-        'event_transaction_type': unicode(get_event_transaction_type()),
+        'course_key': six.text_type(kwargs.get('course_key')),
+        'grading_policy_hash': six.text_type(kwargs.get('grading_policy_hash')),
+        'event_transaction_id': six.text_type(get_event_transaction_id()),
+        'event_transaction_type': six.text_type(get_event_transaction_type()),
     }
     result = task_compute_all_grades_for_course.apply_async(kwargs=kwargs, countdown=GRADING_POLICY_COUNTDOWN_SECONDS)
     log.info(u"Grades: Created {task_name}[{task_id}] with arguments {kwargs}".format(

cms/djangoapps/contentstore/signals/signals.py

 """
 Contentstore signals
 """
+from __future__ import absolute_import
+
 from django.dispatch import Signal
 
 # Signal that indicates that a course grading policy has been updated.

cms/djangoapps/contentstore/tests/test_course_create_rerun.py

 """
 Test view handler for rerun (and eventually create)
 """
+from __future__ import absolute_import
+
 import datetime
 
 import ddt
-from django.urls import reverse
+import six
 from django.test.client import RequestFactory
+from django.urls import reverse
 from mock import patch
 from opaque_keys.edx.keys import CourseKey
 
@@ -68,7 +71,7 @@ class TestCourseListing(ModuleStoreTestCase):
         Just testing the functionality the view handler adds over the tasks tested in test_clone_course
         """
         response = self.client.ajax_post(self.course_create_rerun_url, {
-            'source_course_key': unicode(self.source_course_key),
+            'source_course_key': six.text_type(self.source_course_key),
             'org': self.source_course_key.org, 'course': self.source_course_key.course, 'run': 'copy',
             'display_name': 'not the same old name',
         })

cms/djangoapps/contentstore/tests/test_import.py

@@ -3,12 +3,13 @@
 """
 Tests for import_course_from_xml using the mongo modulestore.
 """
-from __future__ import print_function
+from __future__ import absolute_import, print_function
 
 import copy
 from uuid import uuid4
 
 import ddt
+import six
 from django.conf import settings
 from django.test.client import Client
 from django.test.utils import override_settings
@@ -268,7 +269,7 @@ class ContentStoreImportTest(ModuleStoreTestCase):
         self.assertIsNotNone(split_test_module)
 
         remapped_verticals = {
-            key: target_id.make_usage_key('vertical', value) for key, value in groups_to_verticals.iteritems()
+            key: target_id.make_usage_key('vertical', value) for key, value in six.iteritems(groups_to_verticals)
         }
 
         self.assertEqual(remapped_verticals, split_test_module.group_id_to_child)

cms/djangoapps/contentstore/tests/test_request_event.py

 """Tests for CMS's requests to logs"""
+from __future__ import absolute_import
+
 import mock
-from django.urls import reverse
 from django.test import TestCase
+from django.urls import reverse
+from six import unichr  # pylint: disable=W0622
 
 from contentstore.views.helpers import event as cms_user_track
 

cms/djangoapps/contentstore/tests/utils.py

 '''
 Utilities for contentstore tests
 '''
+from __future__ import absolute_import
+
 import json
 import textwrap
 
+import six
 from django.conf import settings
 from django.contrib.auth.models import User
 from django.test.client import Client
@@ -48,7 +51,7 @@ class AjaxEnabledTestClient(Client):
         Convenience method for client post which serializes the data into json and sets the accept type
         to json
         """
-        if not isinstance(data, basestring):
+        if not isinstance(data, six.string_types):
             data = json.dumps(data or {})
         kwargs.setdefault("HTTP_X_REQUESTED_WITH", "XMLHttpRequest")
         kwargs.setdefault("HTTP_ACCEPT", "application/json")
@@ -354,7 +357,7 @@ class CourseTestCase(ProceduralCourseTestMixin, ModuleStoreTestCase):
         course1_asset_attrs = content_store.get_attrs(course1_id.make_asset_key(category, filename))
         course2_asset_attrs = content_store.get_attrs(course2_id.make_asset_key(category, filename))
         self.assertEqual(len(course1_asset_attrs), len(course2_asset_attrs))
-        for key, value in course1_asset_attrs.iteritems():
+        for key, value in six.iteritems(course1_asset_attrs):
             if key in ['_id', 'filename', 'uploadDate', 'content_son', 'thumbnail_location']:
                 pass
             else: