Continued Django 2.0 introductory tutorial section 3 This section describes how to vote in the foreground.

Build a simple form submission page

polls/templates/polls/detail.html

<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 id="choice{{ forloop.counter }}" type="radio" name="choice" value="{{ choice.id }}">
    <label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br />
    {% endfor %}
    <br />
    <input type="submit" name="" id="" value="vote" />
</form>

Code resolution:

• The url submitted by form form is {% url 'poll: vote' question. id%}, which means the vote method of accessing poll / views.py and taking the question id as a parameter.

• Traverse the relevant options of the problem to show in the radio box

• form forms submit data by post

Configure url

polls/urls.py

path('<int:question_id>/vote/', views.vote, name='vote'),

Screenshot of voting page http://127.0.0.1:8000/polls/1/ :

vote.png

View layer processing submission results

polls/views.py

from django.shortcuts import render, get_object_or_404
from django.http import HttpResponse, HttpResponseRedirect
from django.urls import reverse
from .models import Question, Choice
# ...
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):
        return render(request, 'polls/detail.html', {
            'question': question,
            'error_message': "You must select an option",
        })
    else:
        selected_choice.votes += 1
        selected_choice.save()
        return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))

Code resolution:

• request.POST['choice '] receive data submitted by form page

• Add 1 to the number of votes and update the database

Show voting results

polls/views.py

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

results.html

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

<a href="{% url 'polls:detail' question.id %}">Again?</a>

Submit results page http://127.0.0.1:8000/poll/1/results/

result.png

Optimize url and view writing

Another way of writing:
Replace the question? id with the primary key id

polls/urls.py

#_*_coding:utf8_*_
from django.urls import path
from . import views
app_name = 'polls'
urlpatterns = [
    path('', views.IndexView.as_view(), name='index'),
    path('<int:pk>/', views.DetailView.as_view(), name='detail'),
    path('<int:pk>/results/', views.ResultsView.as_view(), name='results'),
    path('<int:question_id>/vote/', views.vote, name='vote'),
]

The corresponding view also needs to be modified to another writing method. The vote method remains the same, which is used to compare the differences between the two writing methods

polls/views.py

#_*_coding:utf8_*_
from django.shortcuts import render, get_object_or_404
from django.http import HttpResponseRedirect
from django.urls import reverse
from django.views import generic 
from .models import Question, Choice

class IndexView(generic.ListView):
    template_name = 'polls/index.html'
    context_object_name = 'latest_question_list'

    def get_queryset(self):
        return Question.objects.order_by('-pub_date')[:5]

class DetailView(generic.DetailView):
    model = Question
    template_name = 'polls/detail.html'

class ResultsView(generic.DetailView):
    model = Question
    template_name = 'polls/results.html'

def vote(request, question_id):
    # ...

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