add missing course Material reference in models

courses/models.py

@@ -18,6 +18,7 @@ from .utils import hash_name
 
 from .videos.models import Video
 from .notes.models import Note
+from .course_material.models import CourseMaterial
 
 import re
 
@@ -334,14 +335,14 @@ class Course(models.Model):
         return iter(professors)
 
     def is_course_assistant(self, user):
-        if user.is_anonymous():
+        if user.is_anonymous:
             return False
 
         return self.get_professor_role(user) == 'assistant'
         # return role =='assistant', 'coordinator'] or user.is_superuser
 
     def is_assistant_or_coordinator(self, user):
-        if user.is_anonymous():
+        if user.is_anonymous:
             return False
 
         if user.is_staff or user.is_superuser:
@@ -396,18 +397,19 @@ class CourseStudent(models.Model):
     def save(self, *args, **kwargs):
         super(CourseStudent, self).save(*args, **kwargs)
 
-        try:
-            receipt = CourseCertification.objects.get(course_student=self)
-        except CourseCertification.DoesNotExist:
-            from base64 import urlsafe_b64encode as ub64
-            from hashlib import sha1
-            from time import time
-            h = ub64(sha1(str(time()) + self.user.last_name.encode('utf-8')).digest()[0:6])
-            receipt = CourseCertification(course_student=self,
-                                          course=self.course,
-                                          type=CourseCertification.TYPES[0][0],
-                                          is_valid=True, link_hash=h)
-            receipt.save()
+        # TODO Move this to Course Certification app, couse this app must not depend on Course Certification.
+        # try:
+        #     receipt = CourseCertification.objects.get(course_student=self)
+        # except CourseCertification.DoesNotExist:
+        #     from base64 import urlsafe_b64encode as ub64
+        #     from hashlib import sha1
+        #     from time import time
+        #     h = ub64(sha1(str(time()) + self.user.last_name.encode('utf-8')).digest()[0:6])
+        #     receipt = CourseCertification(course_student=self,
+        #                                   course=self.course,
+        #                                   type=CourseCertification.TYPES[0][0],
+        #                                   is_valid=True, link_hash=h)
+        #     receipt.save()
 
     @property
     def units_done(self):