使用通用视图

目的

基于 Django 的通用视图可以减少自己视图的代码设计

重写视图

先看不用通用视图的代码，自己实现的视图，要传入请求，然后利用快捷函数 render 返回 HttpResponse

# Create your views here.
from django.http import HttpResponseRedirect
from django.shortcuts import render, get_object_or_404
from django.urls import reverse

from polls.models import Question, Choice


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)


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):
    question = get_object_or_404(Question, pk=question_id)
    return render(request, 'polls/results.html', {'question': question})

django.views 里有个 generic， generic 里有 ListView 和 DetailView 分别实现了常用的列出对象，和对象详情的类，直接从这两个类继承定义自己的视图类，然后重写类属性，指定用到的模板文件。再然后：

• ListView 需要重写 context_object_name 传入模板的上下文对象
• DetailView 需要重写 model 来指定自己写的模型

from django.http import HttpResponseRedirect
from django.shortcuts import get_object_or_404, render
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'


def vote(request, question_id):
    ... # same as above, no changes needed.

重写 url parttern

之前的 urls.py 里指定了传入视图的主键名称（int:question_id 里的 question_id 如下），对应之前实现的视图函数的参数

from django.urls import path

from . import views

app_name = 'polls'  # 为下面的 url 添加一个命名空间

# 如有多个 urlpattern ，按顺序匹配 route
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'),
]

而新的视图里没有指定 url 传入的主键名，所以默认就规定都用 pk 这个 url 里的变量来统一代替

from django.urls import path

from . import views

app_name = 'polls'  # 为下面的 url 添加一个命名空间

# 如有多个 urlpattern ，按顺序匹配 route
urlpatterns = [
    # ex: /polls/
    path('', views.IndexView.as_view(), name='index'),
    # ex: /polls/5/
    path('<int:pk>/', views.DetailView.as_view(), name='detail'),
    # ex: /polls/5/results/
    path('<int:pk>/results/', views.ResultsView.as_view(), name='results'),
    # ex: /polls/5/vote/
    path('<int:question_id>/vote/', views.vote, name='vote'),

总结

• 利用通用视图，让 urls.py 和 views.py 的代码逻辑减少，不用指定主键变量名，因为通用视图默认 pk
• 适合 对象列出，对象详情 这两种非常非常常用的数据检索行为

更多通用视图的文档

https://docs.djangoproject.com/zh-hans/4.0/topics/class-based-views/