Merge pull request #655 from adityacp/bump_django

Bump django version to 3.0.3

19 files changed, 152 insertions, 143 deletions

diff --git a/yaksh/code_server.py b/yaksh/code_server.py
index 75dd9b2..4feb7fd 100644
--- a/yaksh/code_server.py
+++ b/yaksh/code_server.py
@@ -25,7 +25,7 @@ import time
 import requests
 from tornado.ioloop import IOLoop
 from tornado.web import Application, RequestHandler
-from six.moves import urllib
+import urllib
 
 # Local imports
 from .settings import N_CODE_SERVERS, SERVER_POOL_PORT
diff --git a/yaksh/decorators.py b/yaksh/decorators.py
index 81912f0..d584868 100644
--- a/yaksh/decorators.py
+++ b/yaksh/decorators.py
@@ -40,7 +40,7 @@ def email_verified(func):
         user = request.user
         context = {}
         if not settings.IS_DEVELOPMENT:
-            if user.is_authenticated() and user_has_profile(user):
+            if user.is_authenticated and user_has_profile(user):
                 if not user.profile.is_email_verified:
                     context['success'] = False
                     context['msg'] = "Your account is not verified. \
diff --git a/yaksh/evaluator_tests/test_python_evaluation.py b/yaksh/evaluator_tests/test_python_evaluation.py
index ad9b2c2..de973cf 100644
--- a/yaksh/evaluator_tests/test_python_evaluation.py
+++ b/yaksh/evaluator_tests/test_python_evaluation.py
@@ -523,7 +523,6 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
                                 "weight": 0.0
                                 }]
         user_answer = dedent("""
-                                from six.moves import input
                                 input_a = input()
                                 input_b = input()
                                 a = [int(i) for i in input_a.split(',')]
@@ -557,9 +556,8 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
             "weight": 0.0
             }]
         user_answer = dedent("""
-                                from six.moves import input
-                                a = str(input())
-                                b = str(input())
+                                a = input()
+                                b = input()
                                 print(a.count(b))
                              """
                              )
diff --git a/yaksh/language_registry.py b/yaksh/language_registry.py
index ec5dae9..8059681 100644
--- a/yaksh/language_registry.py
+++ b/yaksh/language_registry.py
@@ -1,6 +1,5 @@
 from __future__ import unicode_literals
 import importlib
-import six
 
 # Local imports
 from .settings import code_evaluators
@@ -27,7 +26,7 @@ def create_evaluator_instance(metadata, test_case):
 class _LanguageRegistry(object):
     def __init__(self):
         self._register = {}
-        for language, module in six.iteritems(code_evaluators):
+        for language, module in code_evaluators.items():
             self._register[language] = None
 
     # Public Protocol ##########
diff --git a/yaksh/middleware/one_session_per_user.py b/yaksh/middleware/one_session_per_user.py
index 1ed1786..3b8d302 100644
--- a/yaksh/middleware/one_session_per_user.py
+++ b/yaksh/middleware/one_session_per_user.py
@@ -20,6 +20,13 @@ class OneSessionPerUserMiddleware(object):
           Link: https://docs.djangoproject.com/en/1.5/topics/auth/customizing/
           #extending-the-existing-user-model
     """
+
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        return self.get_response(request)
+
     def process_request(self, request):
         """
             # Documentation:
diff --git a/yaksh/middleware/user_time_zone.py b/yaksh/middleware/user_time_zone.py
index 206c08a..92035e8 100644
--- a/yaksh/middleware/user_time_zone.py
+++ b/yaksh/middleware/user_time_zone.py
@@ -8,6 +8,12 @@ class TimezoneMiddleware(object):
         if user timezone is not available default value 'Asia/Kolkata'
         is activated
     """
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        return self.get_response(request)
+
     def process_request(self, request):
         user = request.user
         user_tz = 'Asia/Kolkata'
diff --git a/yaksh/models.py b/yaksh/models.py
index 065d9cd..12c902b 100644
--- a/yaksh/models.py
+++ b/yaksh/models.py
@@ -258,7 +258,7 @@ class Lesson(models.Model):
     html_data = models.TextField(null=True, blank=True)
 
     # Creator of the lesson
-    creator = models.ForeignKey(User)
+    creator = models.ForeignKey(User, on_delete=models.CASCADE)
 
     # Activate/Deactivate Lesson
     active = models.BooleanField(default=True)
@@ -329,7 +329,8 @@ class Lesson(models.Model):
 
 #############################################################################
 class LessonFile(models.Model):
-    lesson = models.ForeignKey(Lesson, related_name="lesson")
+    lesson = models.ForeignKey(Lesson, related_name="lesson",
+                               on_delete=models.CASCADE)
     file = models.FileField(upload_to=get_file_dir, default=None)
 
     def remove(self):
@@ -477,7 +478,7 @@ class Quiz(models.Model):
 
     is_exercise = models.BooleanField(default=False)
 
-    creator = models.ForeignKey(User, null=True)
+    creator = models.ForeignKey(User, null=True, on_delete=models.CASCADE)
 
     objects = QuizManager()
 
@@ -534,7 +535,7 @@ class Quiz(models.Model):
         except QuestionPaper.DoesNotExist:
             qp = None
         ans_ppr = AnswerPaper.objects.filter(
-            user=user, course=course, question_paper=qp
+            user_id=user.id, course_id=course.id, question_paper_id=qp
         ).order_by("-attempt_number")
         if ans_ppr.exists():
             status = ans_ppr.first().status
@@ -548,7 +549,7 @@ class Quiz(models.Model):
         except QuestionPaper.DoesNotExist:
             qp = None
         ans_ppr = AnswerPaper.objects.filter(
-            user=user, course=course, question_paper=qp
+            user_id=user.id, course_id=course.id, question_paper_id=qp
         ).order_by("-attempt_number")
         if ans_ppr.exists():
             return any([paper.passed for paper in ans_ppr])
@@ -593,8 +594,10 @@ class LearningUnit(models.Model):
     """ Maintain order of lesson and quiz added in the course """
     order = models.IntegerField()
     type = models.CharField(max_length=16)
-    lesson = models.ForeignKey(Lesson, null=True, blank=True)
-    quiz = models.ForeignKey(Quiz, null=True, blank=True)
+    lesson = models.ForeignKey(Lesson, null=True, blank=True,
+                               on_delete=models.CASCADE)
+    quiz = models.ForeignKey(Quiz, null=True, blank=True,
+                             on_delete=models.CASCADE)
     check_prerequisite = models.BooleanField(default=True)
 
     def get_lesson_or_quiz(self):
@@ -612,10 +615,12 @@ class LearningUnit(models.Model):
             self.check_prerequisite = True
 
     def get_completion_status(self, user, course):
-        course_status = CourseStatus.objects.filter(user=user, course=course)
+        course_status = CourseStatus.objects.filter(
+            user_id=user.id, course_id=course.id
+        )
         state = "not attempted"
         if course_status.exists():
-            if self in course_status.first().completed_units.all():
+            if course_status.first().completed_units.filter(id=self.id):
                 state = "completed"
             elif self.type == "quiz":
                 state = self.quiz.get_answerpaper_status(user, course)
@@ -670,7 +675,8 @@ class LearningModule(models.Model):
     name = models.CharField(max_length=255)
     description = models.TextField(default=None, null=True, blank=True)
     order = models.IntegerField(default=0)
-    creator = models.ForeignKey(User, related_name="module_creator")
+    creator = models.ForeignKey(User, related_name="module_creator",
+                                on_delete=models.CASCADE)
     check_prerequisite = models.BooleanField(default=True)
     check_prerequisite_passes = models.BooleanField(default=False)
     html_data = models.TextField(null=True, blank=True)
@@ -847,7 +853,8 @@ class Course(models.Model):
     active = models.BooleanField(default=True)
     code = models.CharField(max_length=128, null=True, blank=True)
     hidden = models.BooleanField(default=False)
-    creator = models.ForeignKey(User, related_name='creator')
+    creator = models.ForeignKey(User, related_name='creator',
+                                on_delete=models.CASCADE)
     students = models.ManyToManyField(User, related_name='students')
     requests = models.ManyToManyField(User, related_name='requests')
     rejected = models.ManyToManyField(User, related_name='rejected')
@@ -876,7 +883,8 @@ class Course(models.Model):
         null=True
     )
 
-    grading_system = models.ForeignKey(GradingSystem, null=True, blank=True)
+    grading_system = models.ForeignKey(GradingSystem, null=True, blank=True,
+                                       on_delete=models.CASCADE)
 
     objects = CourseManager()
 
@@ -1130,9 +1138,10 @@ class CourseStatus(models.Model):
     completed_units = models.ManyToManyField(LearningUnit,
                                              related_name="completed_units")
     current_unit = models.ForeignKey(LearningUnit, related_name="current_unit",
-                                     null=True, blank=True)
-    course = models.ForeignKey(Course)
-    user = models.ForeignKey(User)
+                                     null=True, blank=True,
+                                     on_delete=models.CASCADE)
+    course = models.ForeignKey(Course, on_delete=models.CASCADE)
+    user = models.ForeignKey(User, on_delete=models.CASCADE)
     grade = models.CharField(max_length=255, null=True, blank=True)
     percentage = models.FloatField(default=0.0)
     percent_completed = models.IntegerField(default=0)
@@ -1144,7 +1153,7 @@ class CourseStatus(models.Model):
         if self.is_course_complete():
             self.calculate_percentage()
             if self.course.grading_system is None:
-                grading_system = GradingSystem.objects.get(name='default')
+                grading_system = GradingSystem.objects.get(name__contains='default')
             else:
                 grading_system = self.course.grading_system
             grade = grading_system.get_grade(self.percentage)
@@ -1186,14 +1195,14 @@ class CourseStatus(models.Model):
 
 ###############################################################################
 class ConcurrentUser(models.Model):
-    concurrent_user = models.OneToOneField(User)
+    concurrent_user = models.OneToOneField(User, on_delete=models.CASCADE)
     session_key = models.CharField(max_length=40)
 
 
 ###############################################################################
 class Profile(models.Model):
     """Profile for a user to store roll number and other details."""
-    user = models.OneToOneField(User)
+    user = models.OneToOneField(User, on_delete=models.CASCADE)
     roll_number = models.CharField(max_length=20)
     institute = models.CharField(max_length=128)
     department = models.CharField(max_length=64)
@@ -1271,7 +1280,8 @@ class Question(models.Model):
     snippet = models.TextField(blank=True)
 
     # user for particular question
-    user = models.ForeignKey(User, related_name="user")
+    user = models.ForeignKey(User, related_name="user",
+                             on_delete=models.CASCADE)
 
     # Does this question allow partial grading
     partial_grading = models.BooleanField(default=False)
@@ -1546,7 +1556,8 @@ class Question(models.Model):
 ###############################################################################
 class FileUpload(models.Model):
     file = models.FileField(upload_to=get_upload_dir, blank=True)
-    question = models.ForeignKey(Question, related_name="question")
+    question = models.ForeignKey(Question, related_name="question",
+                                 on_delete=models.CASCADE)
     extract = models.BooleanField(default=False)
     hide = models.BooleanField(default=False)
 
@@ -1580,7 +1591,7 @@ class Answer(models.Model):
     """Answers submitted by the users."""
 
     # The question for which user answers.
-    question = models.ForeignKey(Question)
+    question = models.ForeignKey(Question, on_delete=models.CASCADE)
 
     # The answer submitted by the user.
     answer = models.TextField(null=True, blank=True)
@@ -1655,7 +1666,7 @@ class QuestionPaper(models.Model):
     """Question paper stores the detail of the questions."""
 
     # Question paper belongs to a particular quiz.
-    quiz = models.ForeignKey(Quiz)
+    quiz = models.ForeignKey(Quiz, on_delete=models.CASCADE)
 
     # Questions that will be mandatory in the quiz.
     fixed_questions = models.ManyToManyField(Question)
@@ -1941,10 +1952,10 @@ class AnswerPaperManager(models.Manager):
     def _get_answerpapers_for_quiz(self, questionpaper_id, course_id,
                                    status=False):
         if not status:
-            return self.filter(question_paper_id=questionpaper_id,
+            return self.filter(question_paper_id__in=questionpaper_id,
                                course_id=course_id)
         else:
-            return self.filter(question_paper_id=questionpaper_id,
+            return self.filter(question_paper_id__in=questionpaper_id,
                                course_id=course_id,
                                status="completed")
 
@@ -1986,14 +1997,15 @@ class AnswerPaperManager(models.Manager):
             .distinct()
 
     def get_user_all_attempts(self, questionpaper, user, course_id):
-        return self.filter(question_paper=questionpaper, user=user,
+        return self.filter(question_paper_id__in=questionpaper, user_id=user,
                            course_id=course_id)\
                             .order_by('-attempt_number')
 
     def get_user_data(self, user, questionpaper_id, course_id,
                       attempt_number=None):
         if attempt_number is not None:
-            papers = self.filter(user=user, question_paper_id=questionpaper_id,
+            papers = self.filter(user_id=user.id,
+                                 question_paper_id__in=questionpaper_id,
                                  course_id=course_id,
                                  attempt_number=attempt_number)
         else:
@@ -2011,7 +2023,8 @@ class AnswerPaperManager(models.Manager):
 
     def get_user_best_of_attempts_marks(self, quiz, user_id, course_id):
         best_attempt = 0.0
-        papers = self.filter(question_paper__quiz=quiz, course_id=course_id,
+        papers = self.filter(question_paper__quiz_id=quiz.id,
+                             course_id=course_id,
                              user=user_id).values("marks_obtained")
         if papers:
             best_attempt = max([marks["marks_obtained"] for marks in papers])
@@ -2023,15 +2036,15 @@ class AnswerPaper(models.Model):
     """A answer paper for a student -- one per student typically.
     """
     # The user taking this question paper.
-    user = models.ForeignKey(User)
+    user = models.ForeignKey(User, on_delete=models.CASCADE)
 
     questions = models.ManyToManyField(Question, related_name='questions')
 
     # The Quiz to which this question paper is attached to.
-    question_paper = models.ForeignKey(QuestionPaper)
+    question_paper = models.ForeignKey(QuestionPaper, on_delete=models.CASCADE)
 
     # Answepaper will be unique to the course
-    course = models.ForeignKey(Course, null=True)
+    course = models.ForeignKey(Course, null=True, on_delete=models.CASCADE)
 
     # The attempt number for the question paper.
     attempt_number = models.IntegerField()
@@ -2451,17 +2464,20 @@ class AssignmentUploadManager(models.Manager):
 
 ##############################################################################
 class AssignmentUpload(models.Model):
-    user = models.ForeignKey(User)
-    assignmentQuestion = models.ForeignKey(Question)
+    user = models.ForeignKey(User, on_delete=models.CASCADE)
+    assignmentQuestion = models.ForeignKey(Question, on_delete=models.CASCADE)
     assignmentFile = models.FileField(upload_to=get_assignment_dir)
-    question_paper = models.ForeignKey(QuestionPaper, blank=True, null=True)
-    course = models.ForeignKey(Course, null=True, blank=True)
+    question_paper = models.ForeignKey(QuestionPaper, blank=True, null=True,
+                                       on_delete=models.CASCADE)
+    course = models.ForeignKey(Course, null=True, blank=True,
+                               on_delete=models.CASCADE)
     objects = AssignmentUploadManager()
 
 
 ##############################################################################
 class TestCase(models.Model):
-    question = models.ForeignKey(Question, blank=True, null=True)
+    question = models.ForeignKey(Question, blank=True, null=True,
+                                 on_delete=models.CASCADE)
     type = models.CharField(max_length=24, choices=test_case_types, null=True)
 
 
@@ -2598,10 +2614,11 @@ class TestCaseOrder(models.Model):
     """
 
     # Answerpaper of the user.
-    answer_paper = models.ForeignKey(AnswerPaper, related_name="answer_paper")
+    answer_paper = models.ForeignKey(AnswerPaper, related_name="answer_paper",
+                                     on_delete=models.CASCADE)
 
     # Question in an answerpaper.
-    question = models.ForeignKey(Question)
+    question = models.ForeignKey(Question, on_delete=models.CASCADE)
 
     # Order of the test case for a question.
     order = models.TextField()
diff --git a/yaksh/templates/yaksh/add_course.html b/yaksh/templates/yaksh/add_course.html
index 72403ce..97c6f56 100644
--- a/yaksh/templates/yaksh/add_course.html
+++ b/yaksh/templates/yaksh/add_course.html
@@ -23,7 +23,7 @@
                 </li>
                 <li class="nav-item">
                     <a class="nav-link active" href="{% url 'yaksh:add_course' %}">
-                        Add New Course
+                        Add/Edit Course
                     </a>
                 </li>
                 <li class="nav-item dropdown hide">
diff --git a/yaksh/templates/yaksh/add_question.html b/yaksh/templates/yaksh/add_question.html
index 1ad7deb..17cdcfe 100644
--- a/yaksh/templates/yaksh/add_question.html
+++ b/yaksh/templates/yaksh/add_question.html
@@ -1,6 +1,6 @@
 {% extends "manage.html" %}
 {% load custom_filters %}
-{% load staticfiles %}
+{% load static %}
 {% block title %} Add Question {% endblock title %}
 {% block pagetitle %} Add Question {% endblock pagetitle %}
 
diff --git a/yaksh/templates/yaksh/add_quiz.html b/yaksh/templates/yaksh/add_quiz.html
index 57b4d77..5497eeb 100644
--- a/yaksh/templates/yaksh/add_quiz.html
+++ b/yaksh/templates/yaksh/add_quiz.html
@@ -14,6 +14,12 @@
 <script src="{% static 'yaksh/js/jquery-3.3.1.min.js' %}"></script>
 <script src="{% static 'yaksh/js/add_quiz.js' %}"></script>
 <script src="{% static 'yaksh/js/jquery.datetimepicker.full.min.js' %}"></script>
+<script type="text/javascript">
+  $(document).ready(function() {
+    $("#id_start_date_time").datetimepicker({format: 'Y-m-d H:i:s'});
+    $("#id_end_date_time").datetimepicker({format: 'Y-m-d H:i:s'});
+  });
+</script>
 
 {% endblock %}
 {% block onload %} onload="javascript:test();"  {% endblock %}
@@ -44,13 +50,9 @@
   <form name=frm id=frm action="" method="post" >
     {% csrf_token %}
     <center>
-      <table class="table">
+      <table class="table table-responsive-sm">
       {{ form.as_table }}
       </table>
-      <script type="text/javascript">
-        $("#id_start_date_time").datetimepicker({format: 'Y-m-d H:i:s'});
-        $("#id_end_date_time").datetimepicker({format: 'Y-m-d H:i:s'});
-      </script>
       <br/>
       <button class="btn btn-success btn-lg" id="submit" name="questionpaper">
         <i class="fa fa-save">&nbsp;Save</i>
diff --git a/yaksh/templates/yaksh/courses.html b/yaksh/templates/yaksh/courses.html
index c890b86..084d0f6 100644
--- a/yaksh/templates/yaksh/courses.html
+++ b/yaksh/templates/yaksh/courses.html
@@ -29,7 +29,7 @@
                     </li>
                     <li class="nav-item">
                         <a class="nav-link" href="{% url 'yaksh:add_course' %}">
-                            Add New Course
+                            Add/Edit Course
                         </a>
                     </li>
                     <li class="nav-item dropdown hide">
diff --git a/yaksh/templates/yaksh/lessons.html b/yaksh/templates/yaksh/lessons.html
index d75e3e0..e5af061 100644
--- a/yaksh/templates/yaksh/lessons.html
+++ b/yaksh/templates/yaksh/lessons.html
@@ -13,7 +13,7 @@
                 </li>
                 <li class="nav-item">
                     <a class="nav-link" href="{% url 'yaksh:add_course' %}">
-                        Add New Course
+                        Add/Edit Course
                     </a>
                 </li>
                 <li class="nav-item dropdown hide">
diff --git a/yaksh/templates/yaksh/modules.html b/yaksh/templates/yaksh/modules.html
index f98be9d..8da207c 100644
--- a/yaksh/templates/yaksh/modules.html
+++ b/yaksh/templates/yaksh/modules.html
@@ -14,7 +14,7 @@
                 </li>
                 <li class="nav-item">
                     <a class="nav-link" href="{% url 'yaksh:add_course' %}">
-                        Add New Course
+                        Add/Edit Course
                     </a>
                 </li>
                 <li class="nav-item dropdown hide">
diff --git a/yaksh/templates/yaksh/quizzes.html b/yaksh/templates/yaksh/quizzes.html
index d374404..58dec99 100644
--- a/yaksh/templates/yaksh/quizzes.html
+++ b/yaksh/templates/yaksh/quizzes.html
@@ -14,7 +14,7 @@
                 </li>
                 <li class="nav-item">
                     <a class="nav-link" href="{% url 'yaksh:add_course' %}">
-                        Add New Course
+                        Add/Edit Course
                     </a>
                 </li>
                 <li class="nav-item dropdown hide">
diff --git a/yaksh/templates/yaksh/showquestions.html b/yaksh/templates/yaksh/showquestions.html
index 895c345..fdfcc60 100644
--- a/yaksh/templates/yaksh/showquestions.html
+++ b/yaksh/templates/yaksh/showquestions.html
@@ -1,5 +1,5 @@
 {% extends "manage.html" %}
-{% load staticfiles %}
+{% load static %}
 
 {% block title %} Questions {% endblock %}
 
diff --git a/yaksh/templatetags/custom_filters.py b/yaksh/templatetags/custom_filters.py
index a78440d..7dc29d4 100644
--- a/yaksh/templatetags/custom_filters.py
+++ b/yaksh/templatetags/custom_filters.py
@@ -24,12 +24,12 @@ def escape_quotes(value):
     return escape_single_and_double_quotes
 
 
-@register.assignment_tag(name="completed")
+@register.simple_tag(name="completed")
 def completed(answerpaper):
     return answerpaper.filter(status="completed").count()
 
 
-@register.assignment_tag(name="inprogress")
+@register.simple_tag(name="inprogress")
 def inprogress(answerpaper):
     return answerpaper.filter(status="inprogress").count()
 
diff --git a/yaksh/test_views.py b/yaksh/test_views.py
index 61ed3eb..569d4d7 100644
--- a/yaksh/test_views.py
+++ b/yaksh/test_views.py
@@ -11,7 +11,7 @@ import shutil
 from markdown import Markdown
 from django.contrib.auth.models import Group
 from django.contrib.auth import authenticate
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 from django.test import TestCase
 from django.test import Client
 from django.http import Http404
@@ -3888,7 +3888,7 @@ class TestPasswordReset(TestCase):
         # Then
         self.assertEqual(response.context['email'], self.user1.email)
         self.assertEqual(response.status_code, 302)
-        self.assertRedirects(response, '/exam/reset/password_reset/mail_sent/')
+        self.assertRedirects(response, '/exam/reset/password_reset/done/')
 
     def test_password_change_post(self):
         """
diff --git a/yaksh/tests/test_code_server.py b/yaksh/tests/test_code_server.py
index 8237256..f4e73f0 100644
--- a/yaksh/tests/test_code_server.py
+++ b/yaksh/tests/test_code_server.py
@@ -6,7 +6,7 @@ except ImportError:
     from queue import Queue
 from threading import Thread
 import unittest
-from six.moves import urllib
+import urllib
 
 from yaksh.code_server import ServerPool, SERVER_POOL_PORT, submit, get_result
 from yaksh import settings
diff --git a/yaksh/views.py b/yaksh/views.py
index cf7f3b4..b54461f 100644
--- a/yaksh/views.py
+++ b/yaksh/views.py
@@ -21,7 +21,6 @@ from django.contrib import messages
 from taggit.models import Tag
 from django.urls import reverse
 import json
-import six
 from textwrap import dedent
 import zipfile
 from markdown import Markdown
@@ -115,7 +114,7 @@ def index(request, next_url=None):
     """The start page.
     """
     user = request.user
-    if user.is_authenticated():
+    if user.is_authenticated:
         if is_moderator(user):
             return my_redirect('/exam/manage/' if not next_url else next_url)
         return my_redirect("/exam/quizzes/" if not next_url else next_url)
@@ -128,7 +127,7 @@ def user_register(request):
     Create a user and corresponding profile and store roll_number also."""
 
     user = request.user
-    if user.is_authenticated():
+    if user.is_authenticated:
         return my_redirect("/exam/quizzes/")
     context = {}
     if request.method == "POST":
@@ -391,7 +390,7 @@ def add_exercise(request, quiz_id=None, course_id=None):
     else:
         form = ExerciseForm(instance=quiz)
         context["exercise"] = quiz
-        context["course_id"] = course_id
+    context["course_id"] = course_id
     context["form"] = form
     return my_render_to_response(request, 'yaksh/add_exercise.html', context)
 
@@ -403,7 +402,7 @@ def prof_manage(request, msg=None):
     """Take credentials of the user with professor/moderator
     rights/permissions and log in."""
     user = request.user
-    if not user.is_authenticated():
+    if not user.is_authenticated:
         return my_redirect('/exam/login')
     if not is_moderator(user):
         return my_redirect('/exam/')
@@ -412,14 +411,7 @@ def prof_manage(request, msg=None):
         is_trial=False).distinct().order_by("-active")
     paginator = Paginator(courses, 20)
     page = request.GET.get('page')
-    try:
-        courses = paginator.page(page)
-    except PageNotAnInteger:
-        # If page is not an integer, deliver first page.
-        courses = paginator.page(1)
-    except EmptyPage:
-        # If page is out of range (e.g. 9999), deliver last page of results.
-        courses = paginator.page(paginator.num_pages)
+    courses = paginator.get_page(page)
     messages.info(request, msg)
     context = {'user': user, 'objects': courses}
     return my_render_to_response(
@@ -432,7 +424,7 @@ def user_login(request):
 
     user = request.user
     context = {}
-    if user.is_authenticated():
+    if user.is_authenticated:
         return index(request)
 
     next_url = request.GET.get('next')
@@ -1066,14 +1058,7 @@ def courses(request):
 
     paginator = Paginator(courses, 30)
     page = request.GET.get('page')
-    try:
-        courses = paginator.page(page)
-    except PageNotAnInteger:
-        # If page is not an integer, deliver first page.
-        courses = paginator.page(1)
-    except EmptyPage:
-        # If page is out of range (e.g. 9999), deliver last page of results.
-        courses = paginator.page(paginator.num_pages)
+    courses = paginator.get_page(page)
     courses_found = courses.object_list.count()
     context = {'objects': courses, 'created': True,
                'form': form, 'courses_found': courses_found}
@@ -1260,12 +1245,7 @@ def monitor(request, quiz_id=None, course_id=None):
         ).order_by("-active").distinct()
         paginator = Paginator(courses, 30)
         page = request.GET.get('page')
-        try:
-            courses = paginator.page(page)
-        except PageNotAnInteger:
-            courses = paginator.page(1)
-        except EmptyPage:
-            courses = paginator.page(paginator.num_pages)
+        courses = paginator.get_page(page)
         context = {
             "papers": [], "objects": courses, "msg": "Monitor"
         }
@@ -1290,9 +1270,10 @@ def monitor(request, quiz_id=None, course_id=None):
         else:
             attempt_numbers = []
         latest_attempts = []
-        papers = AnswerPaper.objects.filter(question_paper=q_paper,
-                                            course_id=course_id).order_by(
-            'user__profile__roll_number'
+        papers = AnswerPaper.objects.filter(
+            question_paper_id=q_paper.first().id,
+            course_id=course_id).order_by(
+                'user__profile__roll_number'
         )
         users = papers.values_list('user').distinct()
         for auser in users:
@@ -1337,14 +1318,9 @@ def ajax_questions_filter(request):
         filter_dict['language'] = str(language)
     questions = Question.objects.get_queryset().filter(
                 **filter_dict).order_by('id')
-    paginator = Paginator(questions, 10)
+    paginator = Paginator(questions, 30)
     page = request.GET.get('page')
-    try:
-        questions = paginator.page(page)
-    except PageNotAnInteger:
-        questions = paginator.page(1)
-    except EmptyPage:
-        questions = paginator.page(paginator.num_pages)
+    questions = paginator.get_page(page)
     return my_render_to_response(
         request, 'yaksh/ajax_question_filter.html', {
             'questions': questions,
@@ -1538,12 +1514,7 @@ def show_all_questions(request):
     upload_form = UploadFileForm()
     paginator = Paginator(questions, 30)
     page = request.GET.get('page')
-    try:
-        questions = paginator.page(page)
-    except PageNotAnInteger:
-        questions = paginator.page(1)
-    except EmptyPage:
-        questions = paginator.page(paginator.num_pages)
+    questions = paginator.get_page(page)
     context['questions'] = questions
     context['objects'] = questions
     context['all_tags'] = all_tags
@@ -1729,12 +1700,7 @@ def grade_user(request, quiz_id=None, user_id=None, attempt_number=None,
             ).order_by("-active").distinct()
         paginator = Paginator(courses, 30)
         page = request.GET.get('page')
-        try:
-            courses = paginator.page(page)
-        except PageNotAnInteger:
-            courses = paginator.page(1)
-        except EmptyPage:
-            courses = paginator.page(paginator.num_pages)
+        courses = paginator.get_page(page)
         context = {"objects": courses, "msg": "grade"}
 
     if quiz_id is not None:
@@ -1749,9 +1715,8 @@ def grade_user(request, quiz_id=None, user_id=None, attempt_number=None,
         if not course.is_creator(current_user) and not \
                 course.is_teacher(current_user):
             raise Http404('This course does not belong to you')
-
         has_quiz_assignments = AssignmentUpload.objects.filter(
-                                question_paper_id=questionpaper_id
+                                question_paper_id__in=questionpaper_id
                                 ).exists()
         context = {
             "users": user_details,
@@ -1771,7 +1736,7 @@ def grade_user(request, quiz_id=None, user_id=None, attempt_number=None,
             except IndexError:
                 raise Http404('No attempts for paper')
             has_user_assignments = AssignmentUpload.objects.filter(
-                                question_paper_id=questionpaper_id,
+                                question_paper_id__in=questionpaper_id,
                                 user_id=user_id
                                 ).exists()
             user = User.objects.get(id=user_id)
@@ -1792,8 +1757,7 @@ def grade_user(request, quiz_id=None, user_id=None, attempt_number=None,
     if request.method == "POST":
         papers = data['papers']
         for paper in papers:
-            for question, answers in six.iteritems(
-                    paper.get_question_answers()):
+            for question, answers in paper.get_question_answers().items():
                 marks = float(request.POST.get('q%d_marks' % question.id, 0))
                 answer = answers[-1]['answer']
                 answer.set_marks(marks)
@@ -1804,7 +1768,8 @@ def grade_user(request, quiz_id=None, user_id=None, attempt_number=None,
             paper.save()
         messages.success(request, "Student data saved successfully")
 
-        course_status = CourseStatus.objects.filter(course=course, user=user)
+        course_status = CourseStatus.objects.filter(
+            course_id=course.id, user_id=user.id)
         if course_status.exists():
             course_status.first().set_grade()
 
@@ -2641,7 +2606,6 @@ def design_module(request, module_id, course_id=None):
 
         if "Change" in request.POST:
             order_list = request.POST.get("ordered_list")
-            print(order_list)
             if order_list:
                 order_list = order_list.split(",")
                 for order in order_list:
@@ -2926,35 +2890,58 @@ def design_course(request, course_id):
                     learning_module.save()
                     to_add_list.append(learning_module)
                 course.learning_module.add(*to_add_list)
+                messages.success(request, "Modules added successfully")
+            else:
+                messages.warning(request, "Please select atleast one module")
 
         if "Change" in request.POST:
-            order_list = request.POST.get("ordered_list").split(",")
-            for order in order_list:
-                learning_unit, learning_order = order.split(":")
-                if learning_order:
-                    learning_module = course.learning_module.get(
-                        id=learning_unit)
-                    learning_module.order = learning_order
-                    learning_module.save()
+            order_list = request.POST.get("ordered_list")
+            if order_list:
+                order_list = order_list.split(",")
+                for order in order_list:
+                    learning_unit, learning_order = order.split(":")
+                    if learning_order:
+                        learning_module = course.learning_module.get(
+                            id=learning_unit)
+                        learning_module.order = learning_order
+                        learning_module.save()
+                messages.success(request, "Changed order successfully")
+            else:
+                messages.warning(request, "Please select atleast one module")
 
         if "Remove" in request.POST:
             remove_values = request.POST.getlist("delete_list")
             if remove_values:
                 course.learning_module.remove(*remove_values)
+                messages.success(request, "Modules removed successfully")
+            else:
+                messages.warning(request, "Please select atleast one module")
 
         if "change_prerequisite_completion" in request.POST:
             unit_list = request.POST.getlist("check_prereq")
-            for unit in unit_list:
-                learning_module = course.learning_module.get(id=unit)
-                learning_module.toggle_check_prerequisite()
-                learning_module.save()
+            if unit_list:
+                for unit in unit_list:
+                    learning_module = course.learning_module.get(id=unit)
+                    learning_module.toggle_check_prerequisite()
+                    learning_module.save()
+                messages.success(
+                    request, "Changed prerequisite check successfully"
+                )
+            else:
+                messages.warning(request, "Please select atleast one module")
 
         if "change_prerequisite_passing" in request.POST:
             unit_list = request.POST.getlist("check_prereq_passes")
-            for unit in unit_list:
-                learning_module = course.learning_module.get(id=unit)
-                learning_module.toggle_check_prerequisite_passes()
-                learning_module.save()
+            if unit_list:
+                for unit in unit_list:
+                    learning_module = course.learning_module.get(id=unit)
+                    learning_module.toggle_check_prerequisite_passes()
+                    learning_module.save()
+                messages.success(
+                    request, "Changed prerequisite check successfully"
+                )
+            else:
+                messages.warning(request, "Please select atleast one module")
 
     added_learning_modules = course.get_learning_modules()
     all_learning_modules = LearningModule.objects.filter(
@@ -3054,14 +3041,7 @@ def course_status(request, course_id):
     students_no = students.count()
     paginator = Paginator(students, 100)
     page = request.GET.get('page')
-    try:
-        students = paginator.page(page)
-    except PageNotAnInteger:
-        # If page is not an integer, deliver first page.
-        students = paginator.page(1)
-    except EmptyPage:
-        # If page is out of range (e.g. 9999), deliver last page of results.
-        students = paginator.page(paginator.num_pages)
+    students = paginator.get_page(page)
 
     stud_details = [(student, course.get_grade(student),
                      course.get_completion_percent(student),