• Table of contents
• Setup The Environment
• Install Django
• New Django App
  • Initial Framework
    • Create View
  • Connect to a Database
    • Create Model
    • Adding Questions
    • Adding Choices
  • Admin Interface
  • Extending a View With Arguments
  • Dynamic Views
  • 404 Error Page
• Create a Form
• Refactoring
• Static Files
  • CSS
  • Background Image
• Resources

This is a condensed version of the Django tutorial found here

Setup The Environment¶

• Setup a python virtual environment to develop in
  • For Arch Linux use issue #876
  • For FreeBSD use issue #874

Install Django¶

• Switch to the pydev user and activate the virtualenv:
  

  su - pydev
  source ~/venv/new_app/bin/activate
  

• And install Django:
  

  pip install Django
  

New Django App¶

• Create a new Django project:
  

  django-admin startproject www_example_com
  cd www_example_com
  

• Edit the project settings.py file:
  

  vi www_example_com/settings.py
  

  • And add the host IP address of the local development machine:
    

    ALLOWED_HOSTS = ['192.168.1.90']
    

• Test the new app by running the development test web server:
  

  ./manage.py runserver 0.0.0.0:8000
  

  
  NOTE: Press CTRL+C to stop the test web server

• Now create a new simple poll web application:
  

  ./manage.py startapp polls
  

Initial Framework¶

Create View¶

• Create the initial view:
  

  vi polls/views.py
  

  • And add the following:
    

    from django.shortcuts import render
    from django.http import HttpResponse
    
    def index(request):
        return HttpResponse("Hello, world. You're at the polls index.")
    

• Now map the view to a URL by creating:
  

  vi polls/urls.py
  

  • And add the following:
    

    from django.conf.urls import url
    
    from . import views
    
    app_name = 'polls'
    urlpatterns = [
        url(r'^$', views.index, name='index'),
    ]
    

• Next, point the root URLconf at the polls.urls module:
  

  vi www_example_com/urls.py
  

  • And add the URL handler the polls/ part of the web application:
    

    from django.conf.urls import include, url
    from django.contrib import admin
    
    app_name = 'polls'
    urlpatterns = [
        url(r'^polls/', include('polls.urls')),
        url(r'^admin/', admin.site.urls),
    ]
    

• Rerun the development test server:
  

  ./manage.py runserver 0.0.0.0:8000
  

  • And open a web browser and go to http://192.168.1.90/polls
    NOTE: Press CTRL+C to stop the test web server

Connect to a Database¶

• Begin by initializing the database:
  

  ./manage.py migrate
  

Create Model¶

• Create the data model file:
  

  vi polls/models.py
  

  • And add the following to create two data models, Question and Choice:
    

    import datetime
    from django.db import models
    from django.utils import timezone
    
    class Question(models.Model):
        question_text = models.CharField(max_length=200)
        pub_date = models.DateTimeField('date published')
    
        def __str__(self):
            return self.question_text
    
        def was_published_recently(self):
            now = timezone.now()
            return now - datetime.timedelta(days=1) <= self.pub_date <= now
    
    class Choice(models.Model):
        question = models.ForeignKey(Question, on_delete=models.CASCADE)
        choice_text = models.CharField(max_length=200)
        votes = models.IntegerField(default=0)
    
        def __str__(self):
            return self.choice_text
    

• Edit the www_example_com/settings.py file:
  

  vi www_example_com/settings.py
  

  • And add the polls.apps.PollsConfig dotted path to the INSTALLED_APPS setting to include the app in our project:
    

    INSTALLED_APPS = [
        'polls.apps.PollsConfig',
        'django.contrib.admin',
        'django.contrib.auth',
        'django.contrib.contenttypes',
        'django.contrib.sessions',
        'django.contrib.messages',
        'django.contrib.staticfiles',
    ]
    

• Now create the polls data model migrations to update the database structure:
  

  ./manage.py makemigrations polls
  

• Then apply the migration:
  

  ./manage.py migrate
  

Adding Questions¶

• Start the management shell:
  

  ./manage.py shell
  

  • And run the following to create a question:
    

    import django
    from polls.models import Question, Choice
    from django.utils import timezone
    
    q = Question(question_text="What's new?", pub_date=timezone.now())
    q.save()
    

Adding Choices¶

• Start the management shell:
  

  ./manage.py shell
  

  • And run the following to create two choices:
    

    import django
    from polls.models import Question, Choice
    from django.utils import timezone
    
    q = Question.objects.get(pk=1)
    q.choice_set.create(choice_text='Not much', votes=0)
    q.choice_set.create(choice_text='Same Stuff, Different Day', votes=0)
    

Admin Interface¶

• Create an admin user:
  

  ./manage.py createsuperuser
  

• Edit the admin file for the poll app:
  

  vi polls/admin.py
  

  • And add the following to make the poll app modifiable in the admin interface
    

    from django.contrib import admin
    from .models import Question
    
    admin.site.register(Question)
    

• Rerun the development test server:
  

  ./manage.py runserver 0.0.0.0:8000
  

  • And open a web browser and go to http://192.168.1.90/admin
    NOTE: Press CTRL+C to stop the test web server

Extending a View With Arguments¶

• Edit the polls/views.py file:
  

  vi polls/views.py
  

  • Add a few more views to polls/views.py. These views are slightly different, because they take an argument:
    

    # Add after the index function
    def detail(request, question_id):
        return HttpResponse("You're looking at question %s." % question_id)
    
    def results(request, question_id):
        response = "You're looking at the results of question %s." 
        return HttpResponse(response % question_id)
    
    def vote(request, question_id):
        return HttpResponse("You're voting on question %s." % question_id)
    

• Then edit the polls/urls.py file:
  

  vi polls/urls.py
  

  • And add the new views into the polls.urls module by adding the following url() calls:
    

    from django.conf.urls import url
    
    from . import views
    
    app_name = 'polls'
    urlpatterns = [
        url(r'^$', views.index, name='index'),
        url(r'^(?P<question_id>[0-9]+)/$', views.detail, name='detail'),
        url(r'^(?P<question_id>[0-9]+)/results/$', views.results, name='results'),
        url(r'^(?P<question_id>[0-9]+)/vote/$', views.vote, name='vote'),
    ]
    

Dynamic Views¶

• Edit the views of the polls app:
  

  vi polls/views.py
  

  • And refactor the index() view to display the latest 5 poll questions in the system, separated by commas, according to publication date:
    

    from django.http import HttpResponse
    from django.shortcuts import render
    from .models import Question
    
    def index(request):
        latest_question_list = Question.objects.order_by('-pub_date')[:5]
        context = {'latest_question_list': latest_question_list}
        return render(request, 'polls/index.html', context)
    
    # Leave the rest of the views (detail, results, vote) unchanged
    

• Create a directory for templates in the polls app, then another directory in the templates directory for polls:
  

  mkdir polls/templates
  mkdir polls/templates/polls
  

• Then create a template for the index of the polls app:
  

  vi polls/templates/polls/index.html
  

  • And add the following:
    

    {% if latest_question_list %}
        <ul>
        {% for question in latest_question_list %}
            <li><a href="{% url 'polls:detail' question.id %}">{{ question.question_text }}</a></li>
        {% endfor %}
        </ul>
    {% else %}
        <p>No polls are available.</p>
    {% endif %}
    

404 Error Page¶

• Edit the polls app views:
  

  vi polls/views.py
  

  • And refactor the detail() view to display a 404 error for non-existent objects:
    

    from django.shortcuts import get_object_or_404, render
    
    from .models import Question
    # ...
    def detail(request, question_id):
        question = get_object_or_404(Question, pk=question_id)
        return render(request, 'polls/detail.html', {'question': question})
    

• And create a template for the detail page in the polls app:
  

  vi polls/templates/polls/detail.html
  

  • And add the following:
    

    <h1>{{ question.question_text }}</h1>
    <ul>
    {% for choice in question.choice_set.all %}
        <li>{{ choice.choice_text }}</li>
    {% endfor %}
    </ul>
    

Create a Form¶

• Edit the polls app detail template:
  

  vi polls/templates/polls/detail.html
  

  • And refactor the template to add an HTML <form> element:
    

    <h1>{{ question.question_text }}</h1>
    
    {% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}
    
    <form action="{% url 'polls:vote' question.id %}" method="post">
    {% csrf_token %}
    {% for choice in question.choice_set.all %}
        <input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}" />
        <label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br />
    {% endfor %}
    <input type="submit" value="Vote" />
    </form>
    

• Edit the polls app views handler:
  

  vi polls/views.py
  

  • And refactor the vote() and results() functions to create the real versions:
    

    from django.shortcuts import get_object_or_404, render
    from django.http import HttpResponseRedirect, HttpResponse
    from django.urls import reverse
    from .models import Choice, Question
    
    # ...
    def results(request, question_id):
        question = get_object_or_404(Question, pk=question_id)
        return render(request, 'polls/results.html', {'question': question})
    
    def vote(request, question_id):
        question = get_object_or_404(Question, pk=question_id)
        try:
            selected_choice = question.choice_set.get(pk=request.POST['choice'])
        except (KeyError, Choice.DoesNotExist):
            # Redisplay the question voting form.
            return render(request, 'polls/detail.html', {
                'question': question,
                'error_message': "You didn't select a choice.",
            })
        else:
            selected_choice.votes += 1
            selected_choice.save()
            # Always return an HttpResponseRedirect after successfully dealing
            # with POST data. This prevents data from being posted twice if a
            # user hits the Back button.
            return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))
    

• Create the polls app template for the results:
  

  vi polls/templates/polls/results.html
  

  • And add the following:
    

    <h1>{{ question.question_text }}</h1>
    
    <ul>
    {% for choice in question.choice_set.all %}
        <li>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}</li>
    {% endfor %}
    </ul>
    
    <a href="{% url 'polls:detail' question.id %}">Vote again?</a>
    

Refactoring¶

• Edit the polls app URL handler:
  

  vi polls/urls.py
  

  • And refactor the second and third URL regexes that handle the Detail and Results views:
    

    from django.conf.urls import url
    from . import views
    
    app_name = 'polls'
    urlpatterns = [
        url(r'^$', views.IndexView.as_view(), name='index'),
        url(r'^(?P<pk>[0-9]+)/$', views.DetailView.as_view(), name='detail'),
        url(r'^(?P<pk>[0-9]+)/results/$', views.ResultsView.as_view(), name='results'),
        url(r'^(?P<question_id>[0-9]+)/vote/$', views.vote, name='vote'),
    ]
    

• Then edit the polls app views handler:
  

  vi polls/views.py
  

• Refactor the old index(), detail(), and results() views and use Django’s generic views instead:
  

  from django.shortcuts import get_object_or_404, render
  from django.http import HttpResponseRedirect
  from django.urls import reverse
  from django.views import generic
  from django.utils import timezone
  from .models import Choice, Question
  
  class IndexView(generic.ListView):
      template_name = 'polls/index.html'
      context_object_name = 'latest_question_list'
  
      def get_queryset(self):
          """ 
          Return the last five published questions (not including those set to be
          published in the future).
          """ 
          return Question.objects.filter(
              pub_date__lte=timezone.now()
          ).order_by('-pub_date')[:5]
  
  class DetailView(generic.DetailView):
      model = Question
      template_name = 'polls/detail.html'
      def get_queryset(self):
          """ 
          Excludes any questions that aren't published yet.
          """ 
          return Question.objects.filter(pub_date__lte=timezone.now())
  
  class ResultsView(generic.DetailView):
      model = Question
      template_name = 'polls/results.html'
  

Static Files¶

CSS¶

• Create a CSS file for the polls app:
  

  vi polls/static/polls/style.css
  

  • And add the following:
    

    li a {
        color: green;
    }
    

• Next, edit the polls app index.html template:
  

  vi polls/templates/polls/index.html
  

  • An add the following at the top:
    

    {% load static %}
    
    <link rel="stylesheet" type="text/css" href="{% static 'polls/style.css' %}" />
    

Background Image¶

• Create an images subdirectory in the polls/static/polls/ directory:
  

  mkdir polls/static/polls/image
  

  
  NOTE: Inside this directory, put an image called background.gif.

• Then, edit the stylesheet created earlier:
  

  vi polls/static/polls/style.css
  

  • And add the following:
    

    body {
        background: white url("image/background.gif") no-repeat right bottom;
    }
    

• Set the STATIC_ROOT setting to the directory from which you’d like to serve these files:
  

  STATIC_URL = '/static/'
  STATIC_ROOT = os.path.join(BASE_DIR, 'static')
  

• Run the collectstatic management command:
  

  ./manage.py collectstatic
  

Resources¶

• https://docs.djangoproject.com/en/1.10/intro/tutorial01/