Django搭建简单网页的学习笔记 之三（View）

一、编写前台界面views：

1.  编写前台界面需要显示的内容，打开polls/views.py，编写如下代码：

   polls/views.py

   from django.http importHttpResponse

   def index(request):

   return HttpResponse("Hello, world. You're atthe polls index.")

2. 编写自己应用的urls文件，在应用polls下创建urls.py，添加如下代码：

   polls/urls.py

   from django.conf.urls import url

   from . import views

   urlpatterns = [

       url(r'^$', views.index, name='index'),

   ]

3. 在项目的urls文件里指定自己应用的urls文件，打开项目的urls.py，添加如下代码：

   mysite/urls.py

   from django.conf.urls import include, url

   from django.contrib import admin

   urlpatterns = [

       url(r'^polls/', include('polls.urls')),

      url(r'^admin/', include(admin.site.urls)),

   ]

4. 在浏览器中打开http://127.0.0.1:8000/polls就可以看到刚刚写的view，即显示“Hello,world. You're at the polls index.” 

二、编写若干个views界面

同上面的原理是一样的，先写界面内容，再去自己应用的urls里面使用正则表达式指定路径。

1. 在polls/views.py中添加如下代码：

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)

2.在polls/urls.py中指定路径：

polls/urls.py

from django.conf.urls import url

from . import views

urlpatterns = [

    #ex: /polls/

   url(r'^$', views.index, name='index'),

    #ex: /polls/5/

   url(r'^(?P[0-9]+)/$', views.detail, name='detail'),

    #ex: /polls/5/results/

   url(r'^(?P[0-9]+)/results/$', views.results, name='results'),

    #ex: /polls/5/vote/

   url(r'^(?P[0-9]+)/vote/$', views.vote, name='vote'),

]

3.然后就可以在浏览器里输入各种路径，如：

http://127.0.0.1:8000/polls/3：显示“You're looking at question 3.”

http://127.0.0.1:8000/polls/3/results：显示“You're looking at the results ofquestion 3.”

http://127.0.0.1:8000/polls/3/vote：显示“You're voting on question 3.”

三、编写用于显示后台数据的前台界面：

上面的界面内容只是静态的显示一些字符串，接下来是实现从后台读取数据显示在前台界面

修改polls/views.py文件，其他的操作是一样的：

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([p.question_text for pin latest_question_list])

   return HttpResponse(output)

这里导入了models里的Question，然后读取出Question里的内容，病按日期排序。

四、从views.py中分离出template进行界面编写

1. 在应用polls里创建templates文件夹，再在里面创建polls文件夹，在新建的polls里创建index.html文件，打开并编写如下代码：

   {% if latest_question_list %}

      

      {% for question in latest_question_list %}

          

   • {{question.question_text }}

      {% endfor %}

      

   {% else %}

      

   No polls are available.

   {% endif %}

   上面代码是从views.py里分离出来的用来显示最近问题列表的功能，这里分条显示。

2. 然后在polls的views里修改代码如下：

   polls/views.py

    

   from django.http import HttpResponse

   from django.template import RequestContext,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 = RequestContext(request, {

           'latest_question_list': latest_question_list,

       })

       returnHttpResponse(template.render(context))

   这里用loader装载template：polls/index.html，然后再传递上下文给template进行render。

五、用render( )代替HttpResponse，简化代码

代码修改如下：

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)

这样就不用导入loader,RequestContext和HttpResponse了， render本身就是返回一个HttpResponse对象，所以直接返回。

也可以这样修改更简洁：

def index(request):

   latest_question_list = Question.objects.order_by('-pub_date')[:5]

   return render(request, 'polls/index.html', {'latest_question_list':latest_question_list})