ENH: Added a Quiz model and time based papers

Added a model called Quiz which allows the admin to define a quiz on a
date which can be active or deactivated.  Users can take a quiz if one
is active and are given a fixed duration to complete the quiz.  They may
login as many times as needed to finish it but the total time is logged.
Javascript code updates a timer on the page.

3 files changed, 88 insertions, 25 deletions

diff --git a/exam/admin.py b/exam/admin.py
index d40a7d6..8482ef9 100644
--- a/exam/admin.py
+++ b/exam/admin.py
@@ -1,4 +1,5 @@
-from exam.models import Question
+from exam.models import Question, Quiz
 from django.contrib import admin
 
-admin.site.register(Question)
\ No newline at end of file
+admin.site.register(Question)
+admin.site.register(Quiz)
diff --git a/exam/models.py b/exam/models.py
index 1e8ba69..ea60f17 100644
--- a/exam/models.py
+++ b/exam/models.py
@@ -1,13 +1,14 @@
+import datetime
 from django.db import models
 from django.contrib.auth.models import User
 
-
+################################################################################
 class Profile(models.Model):
     """Profile for a user to store roll number and other details."""
     user = models.ForeignKey(User)
     roll_number = models.CharField(max_length=20)
 
-
+################################################################################
 class Question(models.Model):
     """A question in the database."""
     # An optional one-line summary of the question.
@@ -26,6 +27,7 @@ class Question(models.Model):
         return self.summary
 
 
+################################################################################
 class Answer(models.Model):
     """Answers submitted by users.
     """
@@ -41,19 +43,50 @@ class Answer(models.Model):
     def __unicode__(self):
         return self.answer
 
+################################################################################
+class Quiz(models.Model):
+    """A quiz that students will participate in.  One can think of this 
+    as the "examination" event.
+    """
+    
+    # The starting/ending date of the quiz.
+    start_date = models.DateField("Date of the quiz")
     
+    # This is always in minutes.
+    duration = models.IntegerField("Duration of quiz in minutes", default=20)
+    
+    # Is the quiz active.  The admin should deactivate the quiz once it is 
+    # complete.
+    active = models.BooleanField(default=True)
+    
+    # Description of quiz.
+    description = models.CharField(max_length=256)
+    
+    def __unicode__(self):
+        desc = self.description or 'Quiz'
+        return '%s: on %s for %d minutes'%(desc, self.start_date, self.duration)
+
+    
+################################################################################
 class QuestionPaper(models.Model):
     """A question paper for a student -- one per student typically.
     """
     # The user taking this question paper.
     user = models.ForeignKey(User)
+    
+    # The Quiz to which this question paper is attached to.
+    quiz = models.ForeignKey(Quiz)
+    
+    # The time when this paper was started by the user.
+    start_time = models.DateTimeField()
+    
     # User's IP which is logged.
     user_ip = models.CharField(max_length=15)
     # Unused currently.
     key = models.CharField(max_length=10)
 
     # used to allow/stop a user from retaking the question paper.
-    is_active = models.BooleanField(default = True)
+    active = models.BooleanField(default = True)
     
     # The questions (a list of ids separated by '|')
     questions = models.CharField(max_length=128)
@@ -108,7 +141,16 @@ class QuestionPaper(models.Model):
             self.questions = '|'.join(qs)
             self.save()
             return qs[0]
+            
+    def time_left(self):
+        """Return the time remaining for the user in seconds."""
+        dt = datetime.datetime.now() - self.start_time
+        secs = dt.total_seconds()
+        total = self.quiz.duration*60.0
+        remain = max(total - secs, 0)
+        return int(remain)
     
     def __unicode__(self):
         u = self.user
         return u'Question paper for {0} {1}'.format(u.first_name, u.last_name)
+
diff --git a/exam/views.py b/exam/views.py
index 0c48f08..ad8a04f 100644
--- a/exam/views.py
+++ b/exam/views.py
@@ -3,11 +3,12 @@ import string
 import os
 import stat
 from os.path import dirname, pardir, abspath, join, exists
+import datetime
 
 from django.contrib.auth import login, logout, authenticate
 from django.shortcuts import render_to_response, get_object_or_404, redirect
 from django.template import RequestContext
-from exam.models import Question, QuestionPaper, Profile, Answer
+from exam.models import Quiz, Question, QuestionPaper, Profile, Answer
 from exam.forms import UserRegisterForm, UserLoginForm
 from exam.xmlrpc_clients import python_server
 
@@ -26,7 +27,6 @@ def get_user_dir(user):
 def index(request):
     """The start page.
     """
-    # Largely copied from Nishanth's QuestionPaper app.
     user = request.user
     if user.is_authenticated():
         return redirect("/exam/start/")
@@ -82,25 +82,25 @@ def user_login(request):
         return render_to_response('exam/login.html', context,
              context_instance=RequestContext(request))
 
-def show_question(request, q_id):
-    """Show a question if possible."""
-    if len(q_id) == 0:
-        return redirect("/exam/complete")
-    else:
-        return question(request, q_id)
-    
 def start(request):
     user = request.user
     try:
-        old_paper = QuestionPaper.objects.get(user=user)
-        if not old_paper.is_active:
-            return redirect("/exam/complete/")
+        # Right now the app is designed so there is only one active quiz 
+        # at a particular time.
+        quiz = Quiz.objects.get(active=True)
+    except Quiz.DoesNotExist:
+        msg = 'No active quiz found, please contact your '\
+              'instructor/administrator. Please login again thereafter.'
+        return complete(request, reason=msg)
+    try:
+        old_paper = QuestionPaper.objects.get(user=user, quiz=quiz)
         p = old_paper.current_question()
         return redirect('/exam/%s'%p)
     except QuestionPaper.DoesNotExist:
         ip = request.META['REMOTE_ADDR']
         key = gen_key(10)
-        new_paper = QuestionPaper(user=user, user_ip=ip, key=key)
+        new_paper = QuestionPaper(user=user, user_ip=ip, key=key, quiz=quiz)
+        new_paper.start_time = datetime.datetime.now()
         
         # Make user directory.
         user_dir = get_user_dir(user)
@@ -130,11 +130,25 @@ def question(request, q_id):
         paper = QuestionPaper.objects.get(user=request.user)
     except QuestionPaper.DoesNotExist:
         redirect('/exam/start')
-    context = {'question': q, 'paper': paper, 'user': user}
+    time_left = paper.time_left()
+    if time_left == 0:
+        return complete(request, reason='Your time is up!')
+    quiz_name = paper.quiz.description
+    context = {'question': q, 'paper': paper, 'user': user, 
+               'quiz_name': quiz_name, 
+               'time_left': time_left}
     ci = RequestContext(request)
     return render_to_response('exam/question.html', context, 
                               context_instance=ci)
 
+def show_question(request, q_id):
+    """Show a question if possible."""
+    if len(q_id) == 0:
+        msg = 'Congratulations!  You have successfully completed the quiz.'
+        return complete(request, msg)
+    else:
+        return question(request, q_id)
+
 def check(request, q_id):
     user = request.user
     question = get_object_or_404(Question, pk=q_id)
@@ -164,8 +178,14 @@ def check(request, q_id):
 
     ci = RequestContext(request)
     if not success:
+        time_left = paper.time_left()
+        if time_left == 0:
+            return complete(request, reason='Your time is up!')
+            
         context = {'question': question, 'error_message': err_msg,
-                   'paper': paper, 'last_attempt': answer}
+                   'paper': paper, 'last_attempt': answer,
+                   'time_left': time_left}
+
         return render_to_response('exam/question.html', context, 
                                   context_instance=ci)
     else:
@@ -176,17 +196,17 @@ def quit(request):
     return render_to_response('exam/quit.html', 
                               context_instance=RequestContext(request)) 
 
-def complete(request):
+def complete(request, reason=None):
     user = request.user
     yes = True
+    message = reason or 'The quiz has been completed. Thank you.'
     if request.method == 'POST':
         yes = request.POST.get('yes', None)
     if yes:
-        paper = QuestionPaper.objects.get(user=user)
-        paper.is_active = False
-        paper.save()
+        # Logout the user and quit with the message given.
         logout(request)
-        return render_to_response('exam/complete.html')
+        context = {'message': message}
+        return render_to_response('exam/complete.html', context)
     else:
         return redirect('/exam/')