Django来敲门~第一部分【9.使用Django内置视图处理对象简化开发】

from django.shortcuts import render, get_object_or_404

from django.http import HttpResponseRedirect
from django.views import generic
from django.urls import reverse

from .models import Question


# 封装：定义展示应用首页的处理类
class IndexView(generic.ListView):
    # 模板路径
    template_name = "index.html"
    # 指定变量名称，保存查询到的数据
    context_object_name = "question_list"

    # 列表页面，需要查询对应的数据集合
    def get_queryset(self):
        return Question.objects.order_by("-pub_date")


# 封装：定义展示问题详细信息的处理类
class DetailView(generic.DetailView):
    # 指定要展示的数据类型
    model = Question
    # 指定展示的模板页面
    template_name = "details.html"


# 封装：定义展示结果的视图处理类
class ResultView(generic.DetailView):
    model = Question
    template_name = "results.html"


# 定义投票结果
def vote(request, question_id):
    # 获取查询的问题对象
    question = get_object_or_404(Question, pk=question_id)
    print(request.POST)
    try:
        select_choice = question.choice_set.get(pk=request.POST['choice'])
    except Exception as e:
        print(e)
        return render(request, "details.html",
                      {
                          "question": question,
                          "error_message": "你的问题还没有发布解决方案"
                      })
    else:
        # 投票数量增加1
        select_choice.votes += 1
        # 保存到数据库
        select_choice.save()
        # 代码中使用配置的方式跳转到指定的路由
        return HttpResponseRedirect(reverse("polls:results", args=(question.id,)))

from django.conf.urls import url
from . import views

app_name = "polls"

urlpatterns = [
    # url(r"^$", views.index, name="index"),
    # url(r"^(?P<question_id>\d+)$", views.detail, name="detail"),
    # url(r"^(?P<question_id>\d+)/results/$", views.results, name="results"),
    url(r"^$", views.IndexView.as_view(), name="index"),
    url(r"^(?P<pk>\d+)/$", views.DetailView.as_view(), name="detail"),
    url(r"^(?P<pk>\d+)/results/$", views.ResultView.as_view(), name="results"),
    url(r"^(?P<question_id>\d+)/vote/$", views.vote, name="vote"),
]

class ListView(MultipleObjectTemplateResponseMixin, BaseListView):
    """
    Render some list of objects, set by `self.model` or `self.queryset`.
    `self.queryset` can actually be any iterable of items, not just a queryset.
    """
......
class MultipleObjectMixin(ContextMixin):
    """
    A mixin for views manipulating multiple objects.
    """
    allow_empty = True 
    queryset = None
    model = None
    paginate_by = None
    paginate_orphans = 0
    context_object_name = None
    paginator_class = Paginator
    page_kwarg = 'page'
    ordering = None
......
    def get_queryset(self):
        """
        Return the list of items for this view.

        The return value must be an iterable and may be an instance of
        `QuerySet` in which case `QuerySet` specific behavior will be enabled.
        """
......

class DetailView(SingleObjectTemplateResponseMixin, BaseDetailView):
    """
    Render a "detail" view of an object.

    By default this is a model instance looked up from `self.queryset`, but the
    view will support display of *any* object by overriding `self.get_object()`.
    """
......
class SingleObjectMixin(ContextMixin):
    """
    Provides the ability to retrieve a single object for further manipulation.
    """
    model = None
    queryset = None
    slug_field = 'slug'
    context_object_name = None
    slug_url_kwarg = 'slug'
    pk_url_kwarg = 'pk'
    query_pk_and_slug = False  
......

# 基础视图对象工具类，用于进行视图的渲染操作，包含了as_view()处理函数
class View(object):
    """
    Intentionally simple parent class for all views. Only implements
    dispatch-by-method and simple sanity checking.
    """
    ......
    @classonlymethod
    def as_view(cls, **initkwargs):
        """
        Main entry point for a request-response process.
        """
        for key in initkwargs:
        ......
# 用于进行视图模板和数据混合渲染的工具类，可以看到包含了template_name字段
class TemplateResponseMixin(object):
    """
    A mixin that can be used to render a template.
    """
    template_name = None
    template_engine = None
    response_class = TemplateResponse
    content_type = None
......
# 用于封装基础模板渲染页面视图的工具类
class TemplateView(TemplateResponseMixin, ContextMixin, View):
    """
    A view that renders a template.  This view will also pass into the context
    any keyword arguments passed by the URLconf.
    """
......
# 用于请求最终重定向的视图工具类
class RedirectView(View):
    """
    A view that provides a redirect on any GET request.
    """
......