Views and templates

1. Writing more views

   # polls/views.py 
   # views response
   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)
   

   # polls/urls.py
   # adding the following path calls
   from django.urls import path
   from . import views
   
   urlpatterns = [
       # ex: /polls/
       path('', views.index, name='index'),
       # ex: /polls/5/
       path('<int:question_id>/', views.detail, name='detail'),
       # ex: /polls/5/results/
       path('<int:question_id>/results/', views.results, name='results'),
       # ex: /polls/5/vote/
       path('<int:question_id>/vote/', views.vote, name='vote'),
   ]
   

2. Write views that actually do something

   # polls/views.py
   from django.http import HttpResponse
   from .models import Question
   
   def index(request):
       latest_question_list = Question.objects.order_by('-pub_date')[:5]
       output = ', '.join([q.question_text for q in latest_question_list])
       return HttpResponse(output)
   
   # Leave the rest of the views (detail, results, vote) unchanged
   

   # polls/templates/polls/index.html
   # Put the following code in that template
   {% if latest_question_list %}
       <ul>
       {% for question in latest_question_list %}
           <li><a href="/polls/{{ question.id }}/">{{ question.question_text }}</a></li>
       {% endfor %}
       </ul>
   {% else %}
       <p>No polls are available.</p>
   {% endif %}
   

   # polls/views.py
   # update our index view in polls/views.py to use the template
   from django.http import HttpResponse
   from django.template import loader
   from .models import Question
   
   def index(request):
       latest_question_list = Question.objects.order_by('-pub_date')[:5]
       template = loader.get_template('polls/index.html')
       context = {
           'latest_question_list': latest_question_list,
       }
       return HttpResponse(template.render(context, request))
   

3. A Shortcut function: render()

   # polls/views.py
   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)
   

4. A shortcut function: get_object_or_404()

   # polls/views.py
   # Raising a 404 error
   from django.http import Http404
   from django.shortcuts import render
   
   from .models import Question
   # ...
   def detail(request, question_id):
       try:
           question = Question.objects.get(pk=question_id)
       except Question.DoesNotExist:
           raise Http404("Question does not exist")
       return render(request, 'polls/detail.html', {'question': question})
   

   <!-- polls/templates/polls/detail.html -->
   {{ question }}
   

   # polls/views.py
   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})
   

5. Use the template system

   <!-- polls/templates/polls/detail.html -->
   <h1>{{ question.question_text }}</h1>
   <ul>
   {% for choice in question.choice_set.all %}
       <li>{{ choice.choice_text }}</li>
   {% endfor %}
   </ul>
   

6. Removing hardcoded URLs in templates

   <li><a href="/polls/{{ question.id }}/">{{ question.question_text }}</a></li>
   <li><a href="{% url 'detail' question.id %}">{{ question.question_text }}</a></li></pre>    
   

   # the 'name' value as called by the {% url %} template tag
   path('<int:question_id>/', views.detail, name='detail'),
   # added the word 'specifics'
   path('specifics/<int:question_id>/', views.detail, name='detail'),
   

7. Namespacing URL names

   # polls/urls.py
   from django.urls import path
   from . import views
   
   app_name = 'polls'
   urlpatterns = [
       path('', views.index, name='index'),
       path('<int:question_id>/', views.detail, name='detail'),
       path('<int:question_id>/results/', views.results, name='results'),
       path('<int:question_id>/vote/', views.vote, name='vote'),
   ]
   

   polls/templates/polls/index.html
   <li><a href="{% url 'detail' question.id %}">{{ question.question_text }}</a></li>
   to point at the namespaced detail view:
   
   polls/templates/polls/index.html
   <li><a href="{% url 'polls:detail' question.id %}">{{ question.question_text }}</a></li>