Revert "Bulk-reads and Request caching in Course Grade Report"

This reverts commit 16e9636513.

common/djangoapps/course_modes/models.py

@@ -9,11 +9,8 @@ from config_models.models import ConfigurationModel
 from django.core.exceptions import ValidationError
 from django.db import models
 from django.db.models import Q
-from django.dispatch import receiver
 from django.utils.translation import ugettext_lazy as _
 from openedx.core.djangoapps.xmodule_django.models import CourseKeyField
-from request_cache.middleware import ns_request_cached, RequestCache
-
 
 Mode = namedtuple('Mode',
                   [
@@ -144,8 +141,6 @@ class CourseMode(models.Model):
     DEFAULT_SHOPPINGCART_MODE_SLUG = HONOR
     DEFAULT_SHOPPINGCART_MODE = Mode(HONOR, _('Honor'), 0, '', 'usd', None, None, None, None)
 
-    CACHE_NAMESPACE = u"course_modes.CourseMode.cache."
-
     class Meta(object):
         unique_together = ('course_id', 'mode_slug', 'currency')
 
@@ -270,7 +265,6 @@ class CourseMode(models.Model):
         return [mode.to_tuple() for mode in found_course_modes]
 
     @classmethod
-    @ns_request_cached(CACHE_NAMESPACE)
     def modes_for_course(cls, course_id, include_expired=False, only_selectable=True):
         """
         Returns a list of the non-expired modes for a given course id
@@ -672,13 +666,6 @@ class CourseMode(models.Model):
         )
 
 
-@receiver(models.signals.post_save, sender=CourseMode)
-@receiver(models.signals.post_delete, sender=CourseMode)
-def invalidate_course_mode_cache(sender, **kwargs):   # pylint: disable=unused-argument
-    """Invalidate the cache of course modes. """
-    RequestCache.clear_request_cache(name=CourseMode.CACHE_NAMESPACE)
-
-
 class CourseModesArchive(models.Model):
     """
     Store the past values of course_mode that a course had in the past. We decided on having

common/djangoapps/course_modes/tests/test_models.py

@@ -16,7 +16,7 @@ from opaque_keys.edx.locator import CourseLocator
 import pytz
 
 from course_modes.helpers import enrollment_mode_display
-from course_modes.models import CourseMode, Mode, invalidate_course_mode_cache
+from course_modes.models import CourseMode, Mode
 from course_modes.tests.factories import CourseModeFactory
 
 
@@ -31,9 +31,6 @@ class CourseModeModelTest(TestCase):
         self.course_key = SlashSeparatedCourseKey('Test', 'TestCourse', 'TestCourseRun')
         CourseMode.objects.all().delete()
 
-    def tearDown(self):
-        invalidate_course_mode_cache(sender=None)
-
     def create_mode(
             self,
             mode_slug,