Merge pull request #140 from prathamesh920/regrade_papers

Regrade papers

7 files changed, 601 insertions, 60 deletions

diff --git a/yaksh/models.py b/yaksh/models.py
index 71cd258..69dff6d 100644
--- a/yaksh/models.py
+++ b/yaksh/models.py
@@ -14,10 +14,14 @@ from django.core.files import File
 from StringIO import StringIO
 import pytz
 import os
+import stat
+from os.path import join, abspath, dirname, exists
 import shutil
 import zipfile
 import tempfile
 from file_utils import extract_files
+from yaksh.xmlrpc_clients import code_server
+from django.conf import settings
 
 
 languages = (
@@ -195,6 +199,18 @@ class Profile(models.Model):
                                 choices=[(tz, tz) for tz in pytz.common_timezones]
                                 )
 
+    def get_user_dir(self):
+        """Return the output directory for the user."""
+
+        user_dir = join(settings.OUTPUT_DIR, str(self.user.username))
+        if not exists(user_dir):
+            os.makedirs(user_dir)
+            # Make it rwx by others.
+            os.chmod(user_dir, stat.S_IROTH | stat.S_IWOTH | stat.S_IXOTH
+                     | stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR
+                     | stat.S_IRGRP | stat.S_IWGRP | stat.S_IXGRP)
+        return user_dir
+
 
 ###############################################################################
 class Question(models.Model):
@@ -994,6 +1010,71 @@ class AnswerPaper(models.Model):
         if question.type == 'code':
             return self.answers.filter(question=question).order_by('-id')
 
+    def validate_answer(self, user_answer, question, json_data=None):
+        """
+            Checks whether the answer submitted by the user is right or wrong.
+            If right then returns correct = True, success and
+            message = Correct answer.
+            success is True for MCQ's and multiple correct choices because
+            only one attempt are allowed for them.
+            For code questions success is True only if the answer is correct.
+        """
+
+        result = {'success': True, 'error': 'Incorrect answer'}
+        correct = False
+        if user_answer is not None:
+            if question.type == 'mcq':
+                expected_answer = question.get_test_case(correct=True).options
+                if user_answer.strip() == expected_answer.strip():
+                    correct = True
+                    result['error'] = 'Correct answer'
+            elif question.type == 'mcc':
+                expected_answers = []
+                for opt in question.get_test_cases(correct=True):
+                    expected_answers.append(opt.options)
+                if set(user_answer) == set(expected_answers):
+                    result['error'] = 'Correct answer'
+                    correct = True
+            elif question.type == 'code':
+                user_dir = self.user.profile.get_user_dir()
+                json_result = code_server.run_code(question.language,
+                        question.test_case_type, json_data, user_dir)
+                result = json.loads(json_result)
+                if result.get('success'):
+                    correct = True
+        return correct, result
+
+    def regrade(self, question_id):
+        try:
+            question = self.questions.get(id=question_id)
+            msg = 'User: {0}; Quiz: {1}; Question: {2}.\n'.format(
+                    self.user, self.question_paper.quiz.description, question)
+        except Question.DoesNotExist:
+            msg = 'User: {0}; Quiz: {1} Question id: {2}.\n'.format(
+                    self.user, self.question_paper.quiz.description, question_id)
+            return False, msg + 'Question not in the answer paper.'
+        user_answer = self.answers.filter(question=question).last()
+        if not user_answer:
+            return False, msg + 'Did not answer.'
+        if question.type == 'mcc':
+            try:
+                answer = eval(user_answer.answer)
+                if type(answer) is not list:
+                    return False, msg + 'MCC answer not a list.'
+            except Exception as e:
+                return False, msg + 'MCC answer submission error'
+        else:
+            answer = user_answer.answer
+        json_data = question.consolidate_answer_data(answer) \
+                            if question.type == 'code' else None
+        correct, result = self.validate_answer(answer, question, json_data)
+        user_answer.marks = question.points if correct else 0.0
+        user_answer.correct = correct
+        user_answer.error = result.get('error')
+        user_answer.save()
+        self.update_marks('complete')
+        return True, msg
+
     def __unicode__(self):
         u = self.user
         q = self.question_paper.quiz
diff --git a/yaksh/templates/manage.html b/yaksh/templates/manage.html
index a736b0a..63c0ea7 100644
--- a/yaksh/templates/manage.html
+++ b/yaksh/templates/manage.html
@@ -33,6 +33,7 @@
 <li><a href="{{ URL_ROOT }}/exam/manage/courses">Courses</a></li>
 <li><a href="{{ URL_ROOT }}/exam/viewprofile">My Profile</a></li>
 <li><a href="{{ URL_ROOT }}/exam/changepassword">Change Password</a></li>
+<li><a href="{{ URL_ROOT }}/exam/manage/grader"> Grader </a></li>
         </ul>
 <ul style="float:right;">
 <li><strong><a style='cursor:pointer' onClick='location.replace("{{URL_ROOT}}/exam/complete/");'>Log out</a></strong></li>
diff --git a/yaksh/templates/yaksh/regrade.html b/yaksh/templates/yaksh/regrade.html
new file mode 100644
index 0000000..77d8ec4
--- /dev/null
+++ b/yaksh/templates/yaksh/regrade.html
@@ -0,0 +1,165 @@
+{% extends "manage.html" %}
+
+{% block title %} Grader {% endblock title %}
+
+{% block css %}
+<link rel="stylesheet" media="all" type="text/css" href="{{ URL_ROOT }}/static/yaksh/css/bootstrap.css" />
+{% endblock %}
+{% block subtitle %}
+    Grader
+    {% endblock %}
+    {% block script %}
+    <script src="{{ URL_ROOT }}/static/yaksh/js/jquery-1.9.1.min.js"></script>
+    <script src="{{ URL_ROOT }}/static/yaksh/js/bootstrap.min.js"></script>
+    {% endblock %}
+    {% block manage %}
+
+<div class="row">
+ <div class="col-md-3">
+  <ul class="nav nav-pills nav-stacked">
+   <li class="active"><a href="#intro" data-toggle="pill" > Intro </a></li>
+   <li><a href="#questions" data-toggle="pill" > Question-wise regrade </a></li>
+   <li><a href="#quizzes" data-toggle="pill" > Quiz-wise regrade </a></li>
+   <li><a href="#users" data-toggle="pill" > User-wise regrade </a></li>
+  </ul>
+ </div><!--span2-->
+ <div class="col-md-9">
+  <div class="tab-content">
+   <div id="intro" class="tab-pane fade in active">
+    <h3> Regrade </h3>
+    <dl>
+     <dt> Question wise regrade </dt>
+     <dd> You can regrade a question for all answerpapers for a given quiz. </dd>
+     <dt> Quiz wise regrade <dt>
+     <dd> You can regrade an answerpaper for a quiz or a question for the same. </dd>
+     <dt> User wise regrade </dt>
+     <dd> You can regrade an answerpaper for an user or a question for the same. </dd>
+    </dl>
+   </div>
+   <div id="questions" class="tab-pane fade">
+    {% for course in courses %}
+     <div class="well">
+      <h4><span class="label label-info">
+       <a href="#questions_quizzes{{ course.id }}" data-toggle="collapse">Course: {{ course }}</a>
+      </span></h4>
+       <div id="questions_quizzes{{ course.id }}" class="collapse">
+        {% for quiz in course.quiz_set.all %}
+         <p><a href="#questions_questions{{ quiz.id }}" data-toggle="collapse">Quiz: {{ quiz }}</a></p>
+          <div id="questions_questions{{ quiz.id }}" class="collapse">
+           {% with questionpaper=quiz.questionpaper_set.get %}
+            <p class="bg-info"> Questions: </p>
+            <ol class="list-group">
+            {% for question in questionpaper.fixed_questions.all %}
+             <li class="list-group">{{ question.summary }}
+              <a href="{{ URL_ROOT }}/exam/manage/regrade/questionpaper/{{ course.id }}/{{ question.id }}/{{ questionpaper.id }}/"
+              class="btn btn-default btn-sm pull-right"><span class="glyphicon glyphicon-repeat"></span> Regrade </a>
+             </li>
+            {% endfor %}
+            {% for random_set in questionpaper.random_questions.all %}
+             {% for question in random_set.questions.all %}
+              <li class="list-group"> {{ question.summary }}
+               <a href="{{ URL_ROOT }}/exam/manage/regrade/questionpaper/{{ course.id}}/{{ question.id }}/{{ questionpaper.id }}/"
+               class="btn btn-default btn-sm pull-right"><span class="glyphicon glyphicon-repeat"></span> Regrade </a>
+              </li>
+             {% endfor %}
+            {% endfor %}
+            </ol>
+           {% endwith %}<br /><br />
+          </div>
+        {% endfor %}
+      </div>
+     </div><!--well-->
+    {% endfor %}
+   </div>
+
+   <div id="quizzes" class="tab-pane fade">
+    {% for course in courses %}
+    <div class="well">
+     <h4><span class="label label-info">
+      <a href="#quizzes_quizzes{{ course.id }}" data-toggle="collapse">Course: {{ course }}</a>
+     </span></h4>
+     <div id="quizzes_quizzes{{ course.id }}" class="collapse">
+      {% for quiz in course.quiz_set.all %}
+       <p><a href="#quizzes_papers{{ quiz.id }}" data-toggle="collapse">Quiz: {{ quiz }}</a></p>
+       <div id="quizzes_papers{{ quiz.id }}" class="collapse">
+       <ol class="list-group">
+       {% for answerpaper in quiz.questionpaper_set.get.answerpaper_set.all %}
+       <li class="list-group">
+        Username: {{ answerpaper.user.username }}; Name: {{ answerpaper.user.get_full_name }}; Attempt Number: {{ answerpaper.attempt_number}}
+        <a href="{{ URL_ROOT }}/exam/manage/regrade/paper/{{ course.id }}/{{ answerpaper.id }}/"
+        class="btn btn-default btn-sm pull-right"><span class="glyphicon glyphicon-repeat"></span> Regrade whole paper </a>
+        </li>
+         <ol class="list-group">
+          {% for question in answerpaper.questions.all %}
+           <li class="list-group"> {{ question.summary }}
+            <a href="{{ URL_ROOT }}/exam/manage/regrade/answerpaper/{{ course.id }}/{{ question.id }}/{{ answerpaper.id }}/"
+            class="btn btn-default btn-sm pull-right"><span class="glyphicon glyphicon-repeat"></span> Regrade </a>
+           </li>
+          {% endfor %}
+         </ol>
+       {% endfor %}
+       </ol>
+       </div>
+      {% endfor %}
+     </div>
+    </div><!--well-->
+    {% endfor %}
+   </div>
+
+   <div id="users" class="tab-pane fade">
+    {% for course in courses %}
+     <div class="well">
+      <h4><span class="label label-info">
+       <a href="#users_users{{ course.id }}" data-toggle="collapse">Course: {{ course }}</a>
+      </span></h4>
+      <div id="users_users{{ course.id }}" class="collapse">
+       {% for user in course.students.all %}
+        <p><a href="#users_papers{{ user.id }}" data-toggle="collapse"> Answer Papers for {{ user.get_full_name }}</a></p>
+         <div id="users_papers{{ user.id }}" class="collapse">
+         <ol class="list-group">
+         {% for answerpaper in user.answerpaper_set.all %}
+         <li class="list-group"> Quiz: {{answerpaper.question_paper.quiz.description }}; Attempt Number: {{ answerpaper.attempt_number }}
+          <a href="{{ URL_ROOT }}/exam/manage/regrade/paper/{{ course.id }}/{{ answerpaper.id }}/"
+          class="btn btn-default btn-sm pull-right" ><span class="glyphicon glyphicon-repeat"></span> Regrade whole paper </a>
+         </li>
+         <ol class="list-group">
+             {% for question in answerpaper.questions.all %}
+             <li class="list-group"> {{ question.summary }}
+             <a href="{{ URL_ROOT }}/exam/manage/regrade/answerpaper/{{ course.id }}/{{ question.id }}/{{ answerpaper.id }}/"
+                 class="btn btn-default btn-sm pull-right"><span class="glyphicon glyphicon-repeat"></span> Regrade </a>
+             </li>
+             {% endfor %}
+         </ol>
+         {% endfor %}
+     </ol>
+ </div>
+ {% endfor %}
+      </div>
+  </div><!--well-->
+  {% endfor %}
+   </div>
+  </div>
+ </div><!--span10-->
+</div><!--row-->
+
+{% if details %}
+<div>
+    <table class="table">
+        <tbody>
+            {% for detail in details %}
+            {% if detail.0 %}
+            <tr class="success">
+                <td> Graded Successfully </td>
+                {% else%}
+                <tr class="danger">
+                    <td> Did not Grade </td>
+                    {% endif %}
+                    <td> {{ detail.1|linebreaks }} </td>
+                </tr>
+                {% endfor %}
+            </tbody>
+        </table>
+    </div>
+    {% endif %}
+
+    {% endblock %}
diff --git a/yaksh/test_models.py b/yaksh/test_models.py
index 0056638..50ead1d 100644
--- a/yaksh/test_models.py
+++ b/yaksh/test_models.py
@@ -1,7 +1,7 @@
 import unittest
 from yaksh.models import User, Profile, Question, Quiz, QuestionPaper,\
     QuestionSet, AnswerPaper, Answer, Course, StandardTestCase,\
-    StdioBasedTestCase, FileUpload
+    StdioBasedTestCase, FileUpload, McqTestCase
 import json
 from datetime import datetime, timedelta
 from django.utils import timezone
@@ -454,6 +454,9 @@ class AnswerPaperTestCases(unittest.TestCase):
         self.questions = Question.objects.filter(id__in=[1,2,3])
         self.start_time = timezone.now()
         self.end_time = self.start_time + timedelta(minutes=20)
+        self.question1 = self.questions.get(id=1)
+        self.question2 = self.questions.get(id=2)
+        self.question3 = self.questions.get(id=3)
 
         # create answerpaper
         self.answerpaper = AnswerPaper(user=self.user,
@@ -487,6 +490,110 @@ class AnswerPaperTestCases(unittest.TestCase):
         self.answerpaper.answers.add(self.answer_right)
         self.answerpaper.answers.add(self.answer_wrong)
 
+        self.question1.language = 'python'
+        self.question1.test_case_type = 'standardtestcase'
+        self.question1.save()
+        self.question2.language = 'python'
+        self.question2.type = 'mcq'
+        self.question2.test_case_type = 'mcqtestcase'
+        self.question2.save()
+        self.question3.language = 'python'
+        self.question3.type = 'mcc'
+        self.question3.test_case_type = 'mcqtestcase'
+        self.question3.save()
+        self.assertion_testcase = StandardTestCase(
+            question=self.question1,
+            test_case='assert add(1, 3) == 4'
+        )
+        self.assertion_testcase.save()
+        self.mcq_based_testcase = McqTestCase(
+            options = 'a',
+            question=self.question2,
+            correct = True
+        )
+        self.mcq_based_testcase.save()
+        self.mcc_based_testcase = McqTestCase(
+            question=self.question3,
+            options = 'a',
+            correct = True
+        )
+        self.mcc_based_testcase.save()
+
+    def test_validate_and_regrade_mcc_question(self):
+        # Given
+        mcc_answer = ['a']
+        self.answer = Answer(question=self.question3,
+            answer=mcc_answer,
+        )
+        self.answer.save()
+        self.answerpaper.answers.add(self.answer)
+
+        # When
+        json_data = None
+        correct, result = self.answerpaper.validate_answer(mcc_answer,
+                self.question3, json_data)
+
+        # Then
+        self.assertTrue(correct)
+        self.assertTrue(result['success'])
+        self.assertEqual(result['error'], 'Correct answer')
+        self.answer.correct = True
+        self.answer.marks = 1
+
+        # Given
+        self.answer.correct = True
+        self.answer.marks = 1
+
+        self.answer.answer = ['a', 'b']
+        self.answer.save()
+
+        # When
+        details = self.answerpaper.regrade(self.question3.id)
+
+        # Then
+        self.answer = self.answerpaper.answers.filter(question=self.question3).last()
+        self.assertTrue(details[0])
+        self.assertEqual(self.answer.marks, 0)
+        self.assertFalse(self.answer.correct)
+
+    def test_validate_and_regrade_mcq_question(self):
+        # Given
+        mcq_answer = 'a'
+        self.answer = Answer(question=self.question2,
+            answer=mcq_answer,
+        )
+        self.answer.save()
+        self.answerpaper.answers.add(self.answer)
+
+        # When
+        json_data = None
+        correct, result = self.answerpaper.validate_answer(mcq_answer,
+                self.question2, json_data)
+
+        # Then
+        self.assertTrue(correct)
+        self.assertTrue(result['success'])
+        self.assertEqual(result['error'], 'Correct answer')
+        self.answer.correct = True
+        self.answer.marks = 1
+
+        # Given
+        self.answer.correct = True
+        self.answer.marks = 1
+
+        self.answer.answer = 'b'
+        self.answer.save()
+
+        # When
+        details = self.answerpaper.regrade(self.question2.id)
+
+        # Then
+        self.answer = self.answerpaper.answers.filter(question=self.question2).last()
+        self.assertTrue(details[0])
+        self.assertEqual(self.answer.marks, 0)
+        self.assertFalse(self.answer.correct)
+
+
     def test_answerpaper(self):
         """ Test Answer Paper"""
         self.assertEqual(self.answerpaper.user.username, 'demo_user')
@@ -747,7 +854,7 @@ class TestCaseTestCases(unittest.TestCase):
              active=True,
              description='Write to standard output',
              points=1.0,
-             test_case_type="stdiobasedtestcase", 
+             test_case_type="stdiobasedtestcase",
              user=self.user,
              snippet='def myfunc()'
         )
diff --git a/yaksh/test_views.py b/yaksh/test_views.py
index 8a38942..cf547b5 100644
--- a/yaksh/test_views.py
+++ b/yaksh/test_views.py
@@ -1134,9 +1134,7 @@ class TestViewAnswerPaper(TestCase):
 class TestSelfEnroll(TestCase):
     def setUp(self):
         self.client = Client()
-
         self.mod_group = Group.objects.create(name='moderator')
-
         # Create Moderator with profile
         self.user1_plaintext_pass = 'demo1'
         self.user1 = User.objects.create_user(
@@ -1233,3 +1231,202 @@ class TestSelfEnroll(TestCase):
             follow=True
         )
         self.assertRedirects(response, '/exam/manage/')
+
+
+class TestGrader(TestCase):
+    def setUp(self):
+        self.client = Client()
+
+        self.mod_group = Group.objects.create(name='moderator')
+
+        # Create Moderator with profile
+        self.user1_plaintext_pass = 'demo1'
+        self.user1 = User.objects.create_user(
+            username='demo_user1',
+            password=self.user1_plaintext_pass,
+            first_name='user1_first_name',
+            last_name='user1_last_name',
+            email='demo@test.com'
+        )
+
+        Profile.objects.create(
+            user=self.user1,
+            roll_number=10,
+            institute='IIT',
+            department='Chemical',
+            position='Moderator',
+            timezone='UTC'
+        )
+
+        self.user2_plaintext_pass = 'demo2'
+        self.user2 = User.objects.create_user(
+            username='demo_user2',
+            password=self.user2_plaintext_pass,
+            first_name='user2_first_name',
+            last_name='user2_last_name',
+            email='demo2@test.com'
+        )
+
+        Profile.objects.create(
+            user=self.user2,
+            roll_number=10,
+            institute='IIT',
+            department='Aeronautical',
+            position='Moderator',
+            timezone='UTC'
+        )
+
+        # Create Student
+        self.student_plaintext_pass = 'demo_student'
+        self.student = User.objects.create_user(
+            username='demo_student',
+            password=self.student_plaintext_pass,
+            first_name='student_first_name',
+            last_name='student_last_name',
+            email='demo_student@test.com'
+        )
+
+        # Add to moderator group
+        self.mod_group.user_set.add(self.user1)
+        self.mod_group.user_set.add(self.user2)
+
+        self.course = Course.objects.create(name="Python Course",
+            enrollment="Enroll Request", creator=self.user1)
+
+        self.question = Question.objects.create(summary='Dummy', points=1,
+                                               type='code', user=self.user1)
+
+        self.quiz = Quiz.objects.create(time_between_attempts=0, course=self.course,
+                                        description='demo quiz', language='Python')
+
+        self.question_paper = QuestionPaper.objects.create(quiz=self.quiz,
+            total_marks=1.0)
+
+        self.question_paper.fixed_questions.add(self.question)
+        self.question_paper.save()
+
+        self.answerpaper = AnswerPaper.objects.create(user_id=3,
+                attempt_number=1, question_paper=self.question_paper,
+                start_time=timezone.now(), user_ip='101.0.0.1',
+                end_time=timezone.now()+timezone.timedelta(minutes=20))
+
+    def tearDown(self):
+        User.objects.all().delete()
+        Course.objects.all().delete()
+        Question.objects.all().delete()
+        Quiz.objects.all().delete()
+        QuestionPaper.objects.all().delete()
+        AnswerPaper.objects.all().delete()
+
+    def test_grader_denies_anonymous(self):
+        # Given
+        redirect_destination = ('/exam/login/?next=/exam/manage/grader/')
+
+        # When
+        response = self.client.get(reverse('yaksh:grader'), follow=True)
+
+        # Then
+        self.assertRedirects(response, redirect_destination)
+
+
+    def test_grader_denies_students(self):
+        # Given
+        self.client.login(
+            username=self.student.username,
+            password=self.student_plaintext_pass
+        )
+
+        # When
+        response = self.client.get(reverse('yaksh:grader'), follow=True)
+
+        # Then
+        self.assertEqual(response.status_code, 404)
+
+
+    def test_regrade_denies_anonymous(self):
+        # Given
+        redirect_destination = ('/exam/login/?next=/exam/manage/regrade/answerpaper/1/1/1/')
+
+        # When
+        response = self.client.get(reverse('yaksh:regrade',
+            kwargs={'course_id': self.course.id,
+                'question_id': self.question.id,
+                'answerpaper_id': self.answerpaper.id}),
+            follow=True)
+
+        # Then
+        self.assertRedirects(response, redirect_destination)
+
+
+    def test_regrade_denies_students(self):
+        # Given
+        self.client.login(
+            username=self.student.username,
+            password=self.student_plaintext_pass
+        )
+
+        # When
+        response = self.client.get(reverse('yaksh:regrade',
+                kwargs={'course_id': self.course.id,
+                    'question_id': self.question.id,
+                    'answerpaper_id': self.answerpaper.id}),
+                follow=True)
+
+        # Then
+        self.assertEqual(response.status_code, 404)
+
+
+    def test_grader_by_moderator(self):
+        # Given
+        self.client.login(
+            username=self.user1.username,
+            password=self.user1_plaintext_pass
+        )
+
+        # When
+        response = self.client.get(reverse('yaksh:grader'),
+                follow=True)
+
+        # Then
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue('courses' in response.context)
+        self.assertTemplateUsed(response, 'yaksh/regrade.html')
+
+
+    def test_regrade_by_moderator(self):
+        # Given
+        self.client.login(
+            username=self.user1.username,
+            password=self.user1_plaintext_pass
+        )
+
+        # When
+        response = self.client.get(reverse('yaksh:regrade',
+            kwargs={'course_id': self.course.id,
+                'question_id': self.question.id,
+                'answerpaper_id': self.answerpaper.id}),
+            follow=True)
+
+        # Then
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue('courses' in response.context)
+        self.assertTrue('details' in response.context)
+        self.assertTemplateUsed(response, 'yaksh/regrade.html')
+
+
+    def test_regrade_denies_moderator_not_in_course(self):
+        # Given
+        self.client.login(
+            username=self.user2.username,
+            password=self.user2_plaintext_pass
+        )
+
+        # When
+        response = self.client.get(reverse('yaksh:regrade',
+            kwargs={'course_id': self.course.id,
+                'question_id': self.question.id,
+                'answerpaper_id': self.answerpaper.id}),
+            follow=True)
+
+        # Then
+        self.assertEqual(response.status_code, 404)
diff --git a/yaksh/urls.py b/yaksh/urls.py
index fb23c7b..c4619b6 100644
--- a/yaksh/urls.py
+++ b/yaksh/urls.py
@@ -101,6 +101,15 @@ urlpatterns += [
     url(r'^manage/remove_teachers/(?P<course_id>\d+)/$', views.remove_teachers, name='remove_teacher'),
     url(r'^manage/download_questions/$', views.show_all_questions),
     url(r'^manage/upload_questions/$', views.show_all_questions),
+    url(r'^manage/grader/$', views.grader, name='grader'),
+    url(r'^manage/regrade/question/(?P<course_id>\d+)/(?P<question_id>\d+)/$',
+            views.regrade, name='regrade'),
+    url(r'^manage/regrade/questionpaper/(?P<course_id>\d+)/(?P<question_id>\d+)/(?P<questionpaper_id>\d+)/$',
+            views.regrade, name='regrade'),
+    url(r'^manage/regrade/answerpaper/(?P<course_id>\d+)/(?P<question_id>\d+)/(?P<answerpaper_id>\d+)/$',
+            views.regrade, name='regrade'),
+    url(r'^manage/regrade/paper/(?P<course_id>\d+)/(?P<answerpaper_id>\d+)/$',
+            views.regrade, name='regrade'),
     url(r'^manage/(?P<mode>[\w\-]+)/(?P<quiz_id>\d+)/$', views.test_quiz),
     url(r'^manage/create_demo_course/$', views.create_demo_course),
 ]
diff --git a/yaksh/views.py b/yaksh/views.py
index 959d323..4c5b9b8 100644
--- a/yaksh/views.py
+++ b/yaksh/views.py
@@ -1,8 +1,6 @@
 import random
 import string
 import os
-import stat
-from os.path import dirname, pardir, abspath, join, exists
 from datetime import datetime
 import collections
 import csv
@@ -23,7 +21,6 @@ from taggit.models import Tag
 from itertools import chain
 import json
 import zipfile
-
 # Local imports.
 from yaksh.models import get_model_class, Quiz, Question, QuestionPaper, QuestionSet, Course
 from yaksh.models import Profile, Answer, AnswerPaper, User, TestCase, FileUpload,\
@@ -32,13 +29,10 @@ from yaksh.forms import UserRegisterForm, UserLoginForm, QuizForm,\
                 QuestionForm, RandomQuestionForm,\
                 QuestionFilterForm, CourseForm, ProfileForm, UploadFileForm,\
                 get_object_form, FileForm
-from yaksh.xmlrpc_clients import code_server
 from settings import URL_ROOT
 from yaksh.models import AssignmentUpload
 from file_utils import extract_files
 
-# The directory where user data can be saved.
-OUTPUT_DIR = abspath(join(dirname(__file__), 'output'))
 
 
 def my_redirect(url):
@@ -57,19 +51,6 @@ def my_render_to_response(template, context=None, **kwargs):
     return render_to_response(template, context, **kwargs)
 
 
-def get_user_dir(user):
-    """Return the output directory for the user."""
-
-    user_dir = join(OUTPUT_DIR, str(user.username))
-    if not exists(user_dir):
-        os.mkdir(user_dir)
-        # Make it rwx by others.
-        os.chmod(user_dir, stat.S_IROTH | stat.S_IWOTH | stat.S_IXOTH
-                 | stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR
-                 | stat.S_IRGRP | stat.S_IWGRP | stat.S_IXGRP)
-    return user_dir
-
-
 def is_moderator(user):
     """Check if the user is having moderator rights"""
     if user.groups.filter(name='moderator').exists():
@@ -434,7 +415,7 @@ def start(request, questionpaper_id=None, attempt_num=None):
             raise Http404(msg)
         new_paper = quest_paper.make_answerpaper(user, ip, attempt_num)
         # Make user directory.
-        user_dir = get_user_dir(user)
+        user_dir = new_paper.user.profile.get_user_dir()
         return show_question(request, new_paper.current_question(), new_paper)
 
 
@@ -535,7 +516,7 @@ def check(request, q_id, attempt_num=None, questionpaper_id=None):
         # safely in a separate process (the code_server.py) running as nobody.
         json_data = question.consolidate_answer_data(user_answer) \
                         if question.type == 'code' else None
-        correct, result = validate_answer(user, user_answer, question, json_data)
+        correct, result = paper.validate_answer(user_answer, question, json_data)
         if correct:
             new_answer.correct = correct
             new_answer.marks = question.points
@@ -556,40 +537,6 @@ def check(request, q_id, attempt_num=None, questionpaper_id=None):
         return show_question(request, question, paper)
 
 
-def validate_answer(user, user_answer, question, json_data=None):
-    """
-        Checks whether the answer submitted by the user is right or wrong.
-        If right then returns correct = True, success and
-        message = Correct answer.
-        success is True for MCQ's and multiple correct choices because
-        only one attempt are allowed for them.
-        For code questions success is True only if the answer is correct.
-    """
-
-    result = {'success': True, 'error': 'Incorrect answer'}
-    correct = False
-
-    if user_answer is not None:
-        if question.type == 'mcq':
-            expected_answer = question.get_test_case(correct=True).options
-            if user_answer.strip() == expected_answer.strip():
-                correct = True
-                result['error'] = 'Correct answer'
-        elif question.type == 'mcc':
-            expected_answers = []
-            for opt in question.get_test_cases(correct=True):
-                expected_answers.append(opt.options)
-            if set(user_answer) == set(expected_answers):
-                result['error'] = 'Correct answer'
-                correct = True
-        elif question.type == 'code':
-            user_dir = get_user_dir(user)
-            json_result = code_server.run_code(question.language, question.test_case_type, json_data, user_dir)
-            result = json.loads(json_result)
-            if result.get('success'):
-                correct = True
-    return correct, result
-
 
 def quit(request, reason=None, attempt_num=None, questionpaper_id=None):
     """Show the quit page when the user logs out."""
@@ -1237,7 +1184,6 @@ def add_teacher(request, course_id):
                                     context_instance=ci)
 
 
-
 @login_required
 def remove_teachers(request, course_id):
     """  remove user from a course """
@@ -1311,3 +1257,38 @@ def create_demo_course(request):
         msg = "Demo course already created"
     context = {'msg': msg}
     return my_render_to_response('manage.html', context, context_instance=ci)
+
+
+@login_required
+def grader(request, extra_context=None):
+    user = request.user
+    if not is_moderator(user):
+        raise Http404('You are not allowed to view this page!')
+    courses = Course.objects.filter(is_trial=False)
+    user_courses = list(courses.filter(creator=user)) + list(courses.filter(teachers=user))
+    context = {'courses': user_courses}
+    if extra_context:
+        context.update(extra_context)
+    return my_render_to_response('yaksh/regrade.html', context)
+
+
+@login_required
+def regrade(request, course_id, question_id=None, answerpaper_id=None, questionpaper_id=None):
+    user = request.user
+    course = get_object_or_404(Course, pk=course_id)
+    if not is_moderator(user) or (user != course.creator and user not in course.teachers.all()):
+        raise Http404('You are not allowed to view this page!')
+    details = []
+    if answerpaper_id is not None and question_id is None:
+        answerpaper = get_object_or_404(AnswerPaper, pk=answerpaper_id)
+        for question in answerpaper.questions.all():
+            details.append(answerpaper.regrade(question.id))
+    if questionpaper_id is not None and question_id is not None:
+        answerpapers = AnswerPaper.objects.filter(questions=question_id,
+                question_paper_id=questionpaper_id)
+        for answerpaper in answerpapers:
+            details.append(answerpaper.regrade(question_id))
+    if answerpaper_id is not None and question_id is not None:
+        answerpaper = get_object_or_404(AnswerPaper, pk=answerpaper_id)
+        details.append(answerpaper.regrade(question_id))
+    return grader(request, extra_context={'details': details})