Revert "Merge pull request #9241 from mitocw/bdero/readd-ccx-membership-model"

This reverts commit d80e8364, reversing
changes made to fb5506a6.

lms/djangoapps/ccx/models.py

@@ -9,7 +9,6 @@ from django.db import models
 from django.utils.timezone import UTC
 
 from lazy import lazy
-from student.models import CourseEnrollment, AlreadyEnrolledError  # pylint: disable=import-error
 from xmodule_django.models import CourseKeyField, LocationKeyField  # pylint: disable=import-error
 from xmodule.error_module import ErrorDescriptor
 from xmodule.modulestore.django import modulestore
@@ -96,43 +95,6 @@ class CustomCourseForEdX(models.Model):
         return value
 
 
-class CcxMembership(models.Model):
-    """
-    Which students are in a CCX?
-    """
-    ccx = models.ForeignKey(CustomCourseForEdX, db_index=True)
-    student = models.ForeignKey(User, db_index=True)
-    active = models.BooleanField(default=False)
-
-    @classmethod
-    def auto_enroll(cls, student, future_membership):
-        """convert future_membership to an active membership
-        """
-        if not future_membership.auto_enroll:
-            msg = "auto enrollment not allowed for {}"
-            raise ValueError(msg.format(future_membership))
-        membership = cls(
-            ccx=future_membership.ccx, student=student, active=True
-        )
-        try:
-            CourseEnrollment.enroll(
-                student, future_membership.ccx.course_id, check_access=True
-            )
-        except AlreadyEnrolledError:
-            # if the user is already enrolled in the course, great!
-            pass
-
-        membership.save()
-        future_membership.delete()
-
-    @classmethod
-    def memberships_for_user(cls, user, active=True):
-        """
-        active memberships for a user
-        """
-        return cls.objects.filter(student=user, active__exact=active)
-
-
 class CcxFieldOverride(models.Model):
     """
     Field overrides for custom courses.