Tutorial to create django app – P3

Thursday, 28/05/2020

Tram Ho

Part 3 – Create views, templates. Convert view to class-based View

Note from django 3.0 learning material https://docs.djangoproject.com/en/3.0

Lifecycle

Add views

views.py:

<span class="token keyword">from</span> django<span class="token punctuation">.</span>http <span class="token keyword">import</span> HttpResponse
<span class="token keyword">from</span> django<span class="token punctuation">.</span>template <span class="token keyword">import</span> loader
<span class="token keyword">from</span> django<span class="token punctuation">.</span>shortcuts <span class="token keyword">import</span> get_object_or_404<span class="token punctuation">,</span> render

<span class="token keyword">from</span> <span class="token punctuation">.</span>models <span class="token keyword">import</span> Question

<span class="token keyword">def</span> <span class="token function">index</span><span class="token punctuation">(</span>request<span class="token punctuation">)</span><span class="token punctuation">:</span>
    latest_question_list <span class="token operator">=</span> Question<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>order_by<span class="token punctuation">(</span><span class="token string">'-pub_date'</span><span class="token punctuation">)</span><span class="token punctuation">[</span><span class="token punctuation">:</span><span class="token number">5</span><span class="token punctuation">]</span>
    template <span class="token operator">=</span> loader<span class="token punctuation">.</span>get_template<span class="token punctuation">(</span><span class="token string">'polls/index.html'</span><span class="token punctuation">)</span>
    context <span class="token operator">=</span> <span class="token punctuation">{</span>
        <span class="token string">'latest_question_list'</span><span class="token punctuation">:</span> latest_question_list<span class="token punctuation">,</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">return</span> HttpResponse<span class="token punctuation">(</span>template<span class="token punctuation">.</span>render<span class="token punctuation">(</span>context<span class="token punctuation">,</span> request<span class="token punctuation">)</span><span class="token punctuation">)</span>

<span class="token keyword">def</span> <span class="token function">detail</span><span class="token punctuation">(</span>request<span class="token punctuation">,</span> question_id<span class="token punctuation">)</span><span class="token punctuation">:</span>
    question <span class="token operator">=</span> get_object_or_404<span class="token punctuation">(</span>Question<span class="token punctuation">,</span> pk<span class="token operator">=</span>question_id<span class="token punctuation">)</span>
    <span class="token keyword">return</span> render<span class="token punctuation">(</span>request<span class="token punctuation">,</span> <span class="token string">'polls/detail.html'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span><span class="token string">'question'</span><span class="token punctuation">:</span> question<span class="token punctuation">}</span><span class="token punctuation">)</span>

<span class="token keyword">def</span> <span class="token function">results</span><span class="token punctuation">(</span>request<span class="token punctuation">,</span> question_id<span class="token punctuation">)</span><span class="token punctuation">:</span>
    response <span class="token operator">=</span> <span class="token string">"You're looking at the results of question %s."</span>
    <span class="token keyword">return</span> HttpResponse<span class="token punctuation">(</span>response <span class="token operator">%</span> question_id<span class="token punctuation">)</span>

<span class="token keyword">def</span> <span class="token function">vote</span><span class="token punctuation">(</span>request<span class="token punctuation">,</span> question_id<span class="token punctuation">)</span><span class="token punctuation">:</span>
    <span class="token keyword">return</span> HttpResponse<span class="token punctuation">(</span><span class="token string">"You're voting on question %s."</span> <span class="token operator">%</span> question_id<span class="token punctuation">)</span>

from django.http import HttpResponse

from django.template import loader

from django.shortcuts import get_object_or_404, render

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))

def detail(request, question_id):

question = get_object_or_404(Question, pk=question_id)

return render(request, 'polls/detail.html', {'question': question})

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)

Add routes

<span class="token keyword">from</span> django<span class="token punctuation">.</span>urls <span class="token keyword">import</span> path

<span class="token keyword">from</span> <span class="token punctuation">.</span> <span class="token keyword">import</span> views

urlpatterns <span class="token operator">=</span> <span class="token punctuation">[</span>
    path<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> views<span class="token punctuation">.</span>index<span class="token punctuation">,</span> name<span class="token operator">=</span><span class="token string">'index'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
    path<span class="token punctuation">(</span><span class="token string">'&lt;int:question_id&gt;/'</span><span class="token punctuation">,</span> views<span class="token punctuation">.</span>detail<span class="token punctuation">,</span> name<span class="token operator">=</span><span class="token string">'detail'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
    path<span class="token punctuation">(</span><span class="token string">'&lt;int:question_id&gt;/results/'</span><span class="token punctuation">,</span> views<span class="token punctuation">.</span>results<span class="token punctuation">,</span> name<span class="token operator">=</span><span class="token string">'results'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
    path<span class="token punctuation">(</span><span class="token string">'&lt;int:question_id&gt;/vote/'</span><span class="token punctuation">,</span> views<span class="token punctuation">.</span>vote<span class="token punctuation">,</span> name<span class="token operator">=</span><span class="token string">'vote'</span><span class="token punctuation">)</span>
<span class="token punctuation">]</span>

from django.urls import path

from . import views

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')

]

Add template

Default template set in polls/templates/polls

polls/templates/polls/index.html:

<span class="token punctuation">{</span><span class="token operator">%</span> <span class="token keyword">if</span> latest_question_list <span class="token operator">%</span><span class="token punctuation">}</span>
    <span class="token operator">&lt;</span>ul<span class="token operator">&gt;</span>
    <span class="token punctuation">{</span><span class="token operator">%</span> <span class="token keyword">for</span> question <span class="token keyword">in</span> latest_question_list <span class="token operator">%</span><span class="token punctuation">}</span>
        <span class="token operator">&lt;</span>li<span class="token operator">&gt;</span><span class="token operator">&lt;</span>a href<span class="token operator">=</span><span class="token string">"/polls/{{ question.id }}/"</span><span class="token operator">&gt;</span><span class="token punctuation">{</span><span class="token punctuation">{</span> question<span class="token punctuation">.</span>question_text <span class="token punctuation">}</span><span class="token punctuation">}</span><span class="token operator">&lt;</span><span class="token operator">/</span>a<span class="token operator">&gt;</span><span class="token operator">&lt;</span><span class="token operator">/</span>li<span class="token operator">&gt;</span>
    <span class="token punctuation">{</span><span class="token operator">%</span> endfor <span class="token operator">%</span><span class="token punctuation">}</span>
    <span class="token operator">&lt;</span><span class="token operator">/</span>ul<span class="token operator">&gt;</span>
<span class="token punctuation">{</span><span class="token operator">%</span> <span class="token keyword">else</span> <span class="token operator">%</span><span class="token punctuation">}</span>
    <span class="token operator">&lt;</span>p<span class="token operator">&gt;</span>No polls are available<span class="token punctuation">.</span><span class="token operator">&lt;</span><span class="token operator">/</span>p<span class="token operator">&gt;</span>
<span class="token punctuation">{</span><span class="token operator">%</span> endif <span class="token operator">%</span><span class="token punctuation">}</span>

{% 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/templates/polls/detail.html:

<span class="token operator">&lt;</span>h1<span class="token operator">&gt;</span><span class="token punctuation">{</span><span class="token punctuation">{</span> question<span class="token punctuation">.</span>question_text <span class="token punctuation">}</span><span class="token punctuation">}</span><span class="token operator">&lt;</span><span class="token operator">/</span>h1<span class="token operator">&gt;</span>
<span class="token operator">&lt;</span>ul<span class="token operator">&gt;</span>
<span class="token punctuation">{</span><span class="token operator">%</span> <span class="token keyword">for</span> choice <span class="token keyword">in</span> question<span class="token punctuation">.</span>choice_set<span class="token punctuation">.</span><span class="token builtin">all</span> <span class="token operator">%</span><span class="token punctuation">}</span>
    <span class="token operator">&lt;</span>li<span class="token operator">&gt;</span><span class="token punctuation">{</span><span class="token punctuation">{</span> choice<span class="token punctuation">.</span>choice_text <span class="token punctuation">}</span><span class="token punctuation">}</span><span class="token operator">&lt;</span><span class="token operator">/</span>li<span class="token operator">&gt;</span>
<span class="token punctuation">{</span><span class="token operator">%</span> endfor <span class="token operator">%</span><span class="token punctuation">}</span>
<span class="token operator">&lt;</span><span class="token operator">/</span>ul<span class="token operator">&gt;</span>

<h1>{{ question.question_text }}</h1>

<ul>

{% for choice in question.choice_set.all %}

<li>{{ choice.choice_text }}</li>

{% endfor %}

</ul>

Want to change the template path => mysite/settings.py Undefined ????

=> 3 url transfer type:

Cattle type:

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>li</span><span class="token punctuation">&gt;</span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>a</span> <span class="token attr-name">href</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>/polls/{{ question.id }}/<span class="token punctuation">"</span></span><span class="token punctuation">&gt;</span></span>{{ question.question_text }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>a</span><span class="token punctuation">&gt;</span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>li</span><span class="token punctuation">&gt;</span></span>

<li><a href="/polls/{{ question.id }}/">{{ question.question_text }}</a></li>

Type of name transfer of url: in the file polls/urls.py named name='detail' => name is detail:

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>li</span><span class="token punctuation">&gt;</span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>a</span> <span class="token attr-name">href</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>{% url <span class="token punctuation">'</span>detail<span class="token punctuation">'</span> question.id %}<span class="token punctuation">"</span></span><span class="token punctuation">&gt;</span></span>{{ question.question_text }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>a</span><span class="token punctuation">&gt;</span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>li</span><span class="token punctuation">&gt;</span></span>

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

Type of transmission namespace polls and url name detail:

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>li</span><span class="token punctuation">&gt;</span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>a</span> <span class="token attr-name">href</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>{% url <span class="token punctuation">'</span>polls:detail<span class="token punctuation">'</span> question.id %}<span class="token punctuation">"</span></span><span class="token punctuation">&gt;</span></span>{{ question.question_text }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>a</span><span class="token punctuation">&gt;</span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>li</span><span class="token punctuation">&gt;</span></span>

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

urls.py: more app_name = 'polls'

get_object_or_404 and render are shortcuts. Other spellings:

views.py

<span class="token keyword">def</span> <span class="token function">index</span><span class="token punctuation">(</span>request<span class="token punctuation">)</span><span class="token punctuation">:</span>
    latest_question_list <span class="token operator">=</span> Question<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>order_by<span class="token punctuation">(</span><span class="token string">'-pub_date'</span><span class="token punctuation">)</span><span class="token punctuation">[</span><span class="token punctuation">:</span><span class="token number">5</span><span class="token punctuation">]</span>
    template <span class="token operator">=</span> loader<span class="token punctuation">.</span>get_template<span class="token punctuation">(</span><span class="token string">'polls/index.html'</span><span class="token punctuation">)</span>
    context <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token string">'latest_question_list'</span><span class="token punctuation">:</span> latest_question_list<span class="token punctuation">}</span>
    <span class="token keyword">return</span> HttpResponse<span class="token punctuation">(</span>template<span class="token punctuation">.</span>render<span class="token punctuation">(</span>context<span class="token punctuation">,</span> request<span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">def</span> <span class="token function">detail</span><span class="token punctuation">(</span>request<span class="token punctuation">,</span> question_id<span class="token punctuation">)</span><span class="token punctuation">:</span>
    <span class="token keyword">try</span><span class="token punctuation">:</span>
        question <span class="token operator">=</span> Question<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>get<span class="token punctuation">(</span>pk<span class="token operator">=</span>question_id<span class="token punctuation">)</span>
    <span class="token keyword">except</span> Question<span class="token punctuation">.</span>DoesNotExist<span class="token punctuation">:</span>
        <span class="token keyword">raise</span> Http404<span class="token punctuation">(</span><span class="token string">"Question does not exist"</span><span class="token punctuation">)</span>
    <span class="token keyword">return</span> render<span class="token punctuation">(</span>request<span class="token punctuation">,</span> <span class="token string">'polls/detail.html'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span><span class="token string">'question'</span><span class="token punctuation">:</span> question<span class="token punctuation">}</span><span class="token punctuation">)</span>

context = {'latest_question_list': latest_question_list}

try:

question = Question.objects.get(pk=question_id)

except Question.DoesNotExist:

raise Http404("Question does not exist")

Series django first project

Add a Vote function form

polls/templates/polls/detail.html:

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>h1</span><span class="token punctuation">&gt;</span></span>{{ question.question_text }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>h1</span><span class="token punctuation">&gt;</span></span>

{% if error_message %}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>p</span><span class="token punctuation">&gt;</span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>strong</span><span class="token punctuation">&gt;</span></span>{{ error_message }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>strong</span><span class="token punctuation">&gt;</span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>p</span><span class="token punctuation">&gt;</span></span>{% endif %}

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>form</span> <span class="token attr-name">action</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>{% url <span class="token punctuation">'</span>polls:vote<span class="token punctuation">'</span> question.id %}<span class="token punctuation">"</span></span> <span class="token attr-name">method</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>post<span class="token punctuation">"</span></span><span class="token punctuation">&gt;</span></span>
{% csrf_token %}
{% for choice in question.choice_set.all %}
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>input</span> <span class="token attr-name">type</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>radio<span class="token punctuation">"</span></span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>choice<span class="token punctuation">"</span></span> <span class="token attr-name">id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>choice{{ forloop.counter }}<span class="token punctuation">"</span></span> <span class="token attr-name">value</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>{{ choice.id }}<span class="token punctuation">"</span></span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>label</span> <span class="token attr-name">for</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>choice{{ forloop.counter }}<span class="token punctuation">"</span></span><span class="token punctuation">&gt;</span></span>{{ choice.choice_text }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>label</span><span class="token punctuation">&gt;</span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>br</span><span class="token punctuation">&gt;</span></span>
{% endfor %}
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>input</span> <span class="token attr-name">type</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>submit<span class="token punctuation">"</span></span> <span class="token attr-name">value</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Vote<span class="token punctuation">"</span></span><span class="token punctuation">&gt;</span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>form</span><span class="token punctuation">&gt;</span></span>

<h1>{{ question.question_text }}</h1>

{% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}

{% csrf_token %}

{% for choice in question.choice_set.all %}

<label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br>

{% endfor %}

</form>

polls/views.py:

<span class="token keyword">def</span> <span class="token function">vote</span><span class="token punctuation">(</span>request<span class="token punctuation">,</span> question_id<span class="token punctuation">)</span><span class="token punctuation">:</span>
    question <span class="token operator">=</span> get_object_or_404<span class="token punctuation">(</span>Question<span class="token punctuation">,</span> pk<span class="token operator">=</span>question_id<span class="token punctuation">)</span>
    <span class="token keyword">try</span><span class="token punctuation">:</span>
        selected_choice <span class="token operator">=</span> question<span class="token punctuation">.</span>choice_set<span class="token punctuation">.</span>get<span class="token punctuation">(</span>pk<span class="token operator">=</span>request<span class="token punctuation">.</span>POST<span class="token punctuation">[</span><span class="token string">'choice'</span><span class="token punctuation">]</span><span class="token punctuation">)</span>
    <span class="token keyword">except</span> <span class="token punctuation">(</span>KeyError<span class="token punctuation">,</span> Choice<span class="token punctuation">.</span>DoesNotExist<span class="token punctuation">)</span><span class="token punctuation">:</span>
        <span class="token comment"># Redisplay the question voting form.</span>
        <span class="token keyword">return</span> render<span class="token punctuation">(</span>request<span class="token punctuation">,</span> <span class="token string">'polls/detail.html'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
            <span class="token string">'question'</span><span class="token punctuation">:</span> question<span class="token punctuation">,</span>
            <span class="token string">'error_message'</span><span class="token punctuation">:</span> <span class="token string">"You didn't select a choice."</span><span class="token punctuation">,</span>
        <span class="token punctuation">}</span><span class="token punctuation">)</span>
    <span class="token keyword">else</span><span class="token punctuation">:</span>
        selected_choice<span class="token punctuation">.</span>votes <span class="token operator">+=</span> <span class="token number">1</span>
        selected_choice<span class="token punctuation">.</span>save<span class="token punctuation">(</span><span class="token punctuation">)</span>
        <span class="token comment"># Always return an HttpResponseRedirect after successfully dealing</span>
        <span class="token comment"># with POST data. This prevents data from being posted twice if a</span>
        <span class="token comment"># user hits the Back button.</span>
        <span class="token keyword">return</span> HttpResponseRedirect<span class="token punctuation">(</span>reverse<span class="token punctuation">(</span><span class="token string">'polls:results'</span><span class="token punctuation">,</span> args<span class="token operator">=</span><span class="token punctuation">(</span>question<span class="token punctuation">.</span><span class="token builtin">id</span><span class="token punctuation">,</span><span class="token punctuation">)</span><span class="token punctuation">)</span>

try:

selected_choice = question.choice_set.get(pk=request.POST['choice'])

except (KeyError, Choice.DoesNotExist):

# Redisplay the question voting form.

'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,))

View result function

polls/views.py:

<span class="token keyword">def</span> <span class="token function">results</span><span class="token punctuation">(</span>request<span class="token punctuation">,</span> question_id<span class="token punctuation">)</span><span class="token punctuation">:</span>
    question <span class="token operator">=</span> get_object_or_404<span class="token punctuation">(</span>Question<span class="token punctuation">,</span> pk<span class="token operator">=</span>question_id<span class="token punctuation">)</span>
    <span class="token keyword">return</span> render<span class="token punctuation">(</span>request<span class="token punctuation">,</span> <span class="token string">'polls/results.html'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span><span class="token string">'question'</span><span class="token punctuation">:</span> question<span class="token punctuation">}</span><span class="token punctuation">)</span>

return render(request, 'polls/results.html', {'question': question})

polls/templates/polls/results.html:

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>h1</span><span class="token punctuation">&gt;</span></span>{{ question.question_text }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>h1</span><span class="token punctuation">&gt;</span></span>

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>ul</span><span class="token punctuation">&gt;</span></span>
{% for choice in question.choice_set.all %}
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>li</span><span class="token punctuation">&gt;</span></span>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>li</span><span class="token punctuation">&gt;</span></span>
{% endfor %}
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>ul</span><span class="token punctuation">&gt;</span></span>

<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>a</span> <span class="token attr-name">href</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>{% url <span class="token punctuation">'</span>polls:detail<span class="token punctuation">'</span> question.id %}<span class="token punctuation">"</span></span><span class="token punctuation">&gt;</span></span>Vote again?<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>a</span><span class="token punctuation">&gt;</span></span>

<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>

If there are 2 people submitting the exact same file at the same time => the voting result will only increase by 1 unit (expected to be 2) => Research https://docs.djangoproject.com/en/3.0/ref/models/expressions/#avoiding-race-conditions-using-f

class-based view

The views flow above work according to a very basic spec, which is generally taking requests with parameters, then querying and retrieving the template to return a response. Django converts this flow (Function Based Views) into another format (Class Base View):

convert URLconf.
Delete unnecessary views.
Create views based on Django’s generic views.

Correction URLconf polls/urls.py:

<span class="token keyword">from</span> django<span class="token punctuation">.</span>urls <span class="token keyword">import</span> path

<span class="token keyword">from</span> <span class="token punctuation">.</span> <span class="token keyword">import</span> views

app_name <span class="token operator">=</span> <span class="token string">'polls'</span>
urlpatterns <span class="token operator">=</span> <span class="token punctuation">[</span>
    path<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> views<span class="token punctuation">.</span>IndexView<span class="token punctuation">.</span>as_view<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> name<span class="token operator">=</span><span class="token string">'index'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
    path<span class="token punctuation">(</span><span class="token string">'&lt;int:pk&gt;/'</span><span class="token punctuation">,</span> views<span class="token punctuation">.</span>DetailView<span class="token punctuation">.</span>as_view<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> name<span class="token operator">=</span><span class="token string">'detail'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
    path<span class="token punctuation">(</span><span class="token string">'&lt;int:pk&gt;/results/'</span><span class="token punctuation">,</span> views<span class="token punctuation">.</span>ResultsView<span class="token punctuation">.</span>as_view<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> name<span class="token operator">=</span><span class="token string">'results'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
    path<span class="token punctuation">(</span><span class="token string">'&lt;int:question_id&gt;/vote/'</span><span class="token punctuation">,</span> views<span class="token punctuation">.</span>vote<span class="token punctuation">,</span> name<span class="token operator">=</span><span class="token string">'vote'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">]</span>

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'),

]

Correction views: polls/views.py

<span class="token keyword">from</span> django<span class="token punctuation">.</span>http <span class="token keyword">import</span> HttpResponseRedirect
<span class="token keyword">from</span> django<span class="token punctuation">.</span>shortcuts <span class="token keyword">import</span> get_object_or_404<span class="token punctuation">,</span> render
<span class="token keyword">from</span> django<span class="token punctuation">.</span>urls <span class="token keyword">import</span> reverse
<span class="token keyword">from</span> django<span class="token punctuation">.</span>views <span class="token keyword">import</span> generic

<span class="token keyword">from</span> <span class="token punctuation">.</span>models <span class="token keyword">import</span> Choice<span class="token punctuation">,</span> Question


<span class="token keyword">class</span> <span class="token class-name">IndexView</span><span class="token punctuation">(</span>generic<span class="token punctuation">.</span>ListView<span class="token punctuation">)</span><span class="token punctuation">:</span>
    template_name <span class="token operator">=</span> <span class="token string">'polls/index.html'</span>
    context_object_name <span class="token operator">=</span> <span class="token string">'latest_question_list'</span>

    <span class="token keyword">def</span> <span class="token function">get_queryset</span><span class="token punctuation">(</span>self<span class="token punctuation">)</span><span class="token punctuation">:</span>
        <span class="token triple-quoted-string string">"""Return the last five published questions."""</span>
        <span class="token keyword">return</span> Question<span class="token punctuation">.</span>objects<span class="token punctuation">.</span>order_by<span class="token punctuation">(</span><span class="token string">'-pub_date'</span><span class="token punctuation">)</span><span class="token punctuation">[</span><span class="token punctuation">:</span><span class="token number">5</span><span class="token punctuation">]</span>


<span class="token keyword">class</span> <span class="token class-name">DetailView</span><span class="token punctuation">(</span>generic<span class="token punctuation">.</span>DetailView<span class="token punctuation">)</span><span class="token punctuation">:</span>
    model <span class="token operator">=</span> Question
    template_name <span class="token operator">=</span> <span class="token string">'polls/detail.html'</span>


<span class="token keyword">class</span> <span class="token class-name">ResultsView</span><span class="token punctuation">(</span>generic<span class="token punctuation">.</span>DetailView<span class="token punctuation">)</span><span class="token punctuation">:</span>
    model <span class="token operator">=</span> Question
    template_name <span class="token operator">=</span> <span class="token string">'polls/results.html'</span>


<span class="token keyword">def</span> <span class="token function">vote</span><span class="token punctuation">(</span>request<span class="token punctuation">,</span> question_id<span class="token punctuation">)</span><span class="token punctuation">:</span>
    <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token comment"># same as above, no changes needed.</span>

from django.http import HttpResponseRedirect

from django.urls import reverse

from django.views import generic

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."""

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'

... # same as above, no changes needed.

generic.ListView, generic.DetailView These are classes that abstract the process of handling specific objects, perform most of the basic processing called collectively Class Base View
template_name = polls/details.html: Specifies the template name instead of the default ("polls/question_detail.html")
context_object_name = 'latest_question_list' Specifies the return variable name for the template, otherwise in this context the default variable name will be question_list
get_queryset: There are a bunch of query helper methods called queryset, In this case, override the method to get 5 questions by pub_date.

Share the news now

Source : Viblo

Tutorial to create django app – P3

Part 3 – Create views, templates. Convert view to class-based View

Lifecycle

Add views

Add routes

Add template

Series django first project

Add a Vote function form

View result function

class-based view

TikTok becomes the second largest social platform in South Africa

The fastest depreciating after 9 months of launch, iPhone 14 Pro Max continues to break the bottom in Vietnam

Beginner's guide to R: Introduction

10 essential SublimeText plugins for JavaScript developers