View

In Django, each view is represented by a simple python function.

To get from a URL to view, Django uses what are know as 'URLconfs'. A URL conf maps URL patterns to views.

Now we edit the samapp views.py to add three functions.They are 'detail', 'results' and vote'.

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 we should edit the 'samapp/urls.py' file to take the three functions in action.

# /samapp/url(r'^$', views.index, name='index'),# /samapp/23/url(r'^(?P
    
     [0-9]+)/$', views.detail, name='detail'),# /samapp/23/results/url(r'^(?P
     
      [0-9]+)/results/$', views.results, name='results'),# /samapp/23/vote/    url(r'^(?P
      
       [0-9]+)/vote/$', views.vote, name='vote'),
      
     
    

A view that actually do something

views.py

def index(request):    latest_question_list = Question.objects.order_by('-pub_date')[:5]    output = ', '.join([q.question_teext for q in latest_question_list])    #return HttpResponse("Hello, this is sam site.")    return HttpResponse(output)

Template system

Next, let's use Django's template system to separate the design from python by creating a template that the view can use.

The template file position should like below.

├─samapp│  ││  ├─templates│  │  └─samapp│  │          index.html

index.html

{% if latest_question_list %}    
    
             {% for question in latest_question_list %}            
     
                                    {
   { question.question_text }}                            
    
    
{% else %}    
No polls are available.
{% endif %}

Then, we update the samapp/views.py to use the template.

def index(request):    latest_question_list = Question.objects.order_by('-pub_date')[:5]    template = loader.get_template('samapp/index.html')    context = RequestContext(request, {'latest_question_list': latest_question_list})    return HttpResponse(template.render(context))

A shortcut: render()

from django.shortcuts import renderfrom .models import Questiondef 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)

A shortcut: get_object_or_404()

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

Removing hardcoded URLs in templates

As before, in the template, the link war partially hardcoded link this:

    {
   { question.question_text }}

That is tightly-coupled approached with url '/samapp/'.So, we'd better do like this.

{
   { question.question_text }}

This will look up the URL definition in the samapp/urls.py file. And if you want to change the URL, you would change only int the samapp/urls.py file.

Namespacing URL names

When we have more than one apps, we will encounter a problem.

The url name may be the same. So, we should add namespaces to our URL conf.

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

Now, change the template from the origin to the below.

{
   { question.question_text }}