Django基于类的视图(views)

一个视图(view)是一个可调用对象(callable), 不仅仅局限于一个函数。
https://docs.djangoproject.com/en/1.8/ref/class-based-views/
== 介绍

基于类的视图(class-based views)相比较于基于函数的视图(function-based views)的不同和优点：

* 处理不同HTTP方法(GET,POST,etc)的代码可以定位到不同的函数，而不是使用不同条件分支。

* 如mixin(多重继承)的面相对象技术，可以用于将代码组织成可以复用的模块。

- 使用基于类的视图(view)

from django.http import HttpResponse

from django.views.generic import View

class MyView(View):

def get(self, request):

# <view logic>

return HttpResponse('result')

在基于类的方法中，你没有必要使返回与基于函数的方法保持一致，即返回某种形式的HttpResponse.

意味着http shortcuts和TemplateResponse对象在基于类的方法中可用。

有两种方法设置类的属性：

class MorningGreetingView(GreetingView):

greeting = "Morning to ya"

或

urlpatterns = [

url(r'^about/', GreetingView.as_view(greeting="G'day")),

]

- 使用Mixins

Mixins是一种形式的多重继承，多个父类的行为和方法可以被组合。

- 处理forms

from .forms import MyForm

class MyFormView(View):

form_class = MyForm

initial = {'key': 'value'}

template_name = 'form_template.html'

def get(self, request, *args, **kwargs):

form = self.form_class(initial=self.initial)

return render(request, self.template_name, {'form': form})

def post(self, request, *args, **kwargs):

form = self.form_class(request.POST)

if form.is_valid():

# <process form cleaned data>

return HttpResponseRedirect('/success/')

return render(request, self.template_name, {'form': form})

- 修饰符

from django.contrib.auth.decorators import login_required, permission_required

from django.views.generic import TemplateView

from .views import VoteView

urlpatterns = [

url(r'^about/', login_required(TemplateView.as_view(template_name="secret.html"))),

url(r'^vote/', permission_required('polls.can_vote')(VoteView.as_view())),

]

class ProtectedView(TemplateView):

template_name = 'secret.html'

@method_decorator(login_required)

def dispatch(self, *args, **kwargs):

return super(ProtectedView, self).dispatch(*args, **kwargs)

== 内建的基于类的通用显示视图(generic views)

* 为单个对象显示列表和详情页面

* 为基于日期的对象按year/month/day显示归档页面，及详情、最近页面。

* 允许用户create,update,delete对象 - 在认证或未认证情况下。

- 扩展通用视图

推荐通过继承子类和override属性及方法来扩展generic views,而不是在URLCong中传入大量配置。

- 通用视图对象

# models.py

from django.db import models

class Publisher(models.Model):

只需添加下列代码：

# views.py

class PublisherList(ListView):

model = Publisher # queryset = Publisher.objects.all()

# urls.py

urlpatterns = [

url(r'^publishers/$', PublisherList.as_view()),

]

当然，还需要写一个模板(template).

我们可以显示的通过添加template_name属性指明template路径，

如果不显示指定，Django根据对象名使用默认路径"books/publisher_list.html"

# 渲染时context包含一个object_list变量包含所有对象，及publisher_list

{% extends "base.html" %}

{% block content %}

<h2>Publishers</h2>

<ul>

{% for publisher in object_list %}

<li>{{ publisher.name }}</li>

{% endfor %}

</ul>

{% endblock %}

# context_object_name

class PublisherList(ListView):

model = Publisher

context_object_name = 'my_favorite_publishers'

- 在context中添加其他信息

class PublisherDetail(DetailView):

model = Publisher

def get_context_data(self, **kwargs):

# 获取context

context = super(PublisherDetail, self).get_context_data(**kwargs)

# 添加QuerySet of all the books

context['book_list'] = Book.objects.all()

return context

- 只显示列表子集

class PublisherDetail(DetailView):

context_object_name = 'publisher'

queryset = Publisher.objects.all()[:10]

class BookList(ListView):

queryset = Book.objects.order_by('-publication_date')

context_object_name = 'book_list'

- 动态过滤

urlpatterns = [

url(r'^books/([\w-]+)/$', PublisherBookList.as_view()),

]

class PublisherBookList(ListView):

template_name = 'books/books_by_publisher.html'

def get_queryset(self):

self.publisher = get_object_or_404(Publisher, name=self.args[0])

return Book.objects.filter(publisher=self.publisher)

def get_context_data(self, **kwargs):

context = super(PublisherBookList, self).get_context_data(**kwargs)

context['publisher'] = self.publisher

return context

- 其他用法

class AuthorDetailView(DetailView):

queryset = Author.objects.all()

def get_object(self): # 获取对象时调用

object = super(AuthorDetailView, self).get_object()

object.last_accessed = timezone.now() # 更新访问时间

object.save()

return object

== 内建的基于类的通用编辑视图 (Forms)

== 在基于类的视图中使用Mixins