3、編寫第一個django應用(投票應用),第三部分簡要過程

第三部分官網參考鏈接 https://docs.djangoproject.com/zh-hans/2.2/intro/tutorial03/
1、編寫更多視圖：
添加函數
polls/views.py

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)

url函數調用
polls/urls.py

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'),
]

訪問：
http://127.0.0.1:8000/polls/
http://127.0.0.1:8000/polls/5
http://127.0.0.1:8000/polls/5/results
http://127.0.0.1:8000/polls/5/vote

2、一個快捷函數： render()的使用
(1) 編寫index視圖

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)

（2）添加模板
polls應用下創建templates/polls子文件夾，再在polls/templates/polls下創建index.html
polls/templates/polls/index.html

{% 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 %}

頁面添加六條數據 http://127.0.0.1:8000/admin
測試訪問：http://127.0.0.1:8000/polls/

3、一個快捷函數： get_object_or_404()執出404錯誤
（1）編寫視圖

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})

添加模板系統
polls/templates/polls/detail.html
{{ question }}

4、爲 URL 名稱添加命名空間
在每個應用的的urls下添加對應的應用名字的命名空間
polls/urls.py

from django.urls import path
from . import views
app_name = 'polls'   #添加命名空間
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'),
]

修改爲指向具有命名空間的詳細視圖：
polls/templates/polls/index.html
<li><a href="{% url 'polls:detail' question.id %}">{{ question.question_text }}</a></li>