Django通用视图执行过程

使用通用视图后，Django请求处理过程(以ListView为例)：
在我们自定义的视图中：

class IndexView(ListView):
    template_name = 'blog/index.html'
    context_object_name = 'article_list'

    def get_context_data(self, **kwargs):
        kwargs['category_list'] = Category.objects.all()
        return super(IndexView, self).get_context_data()

    def get_queryset(self):
        return Article.objects.filter(status=1)

ListView的定义：

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.
    """

View中as_view方法：

class View(object):
    @classonlymethod
    def as_view(cls, **initkwargs):
        """
        Main entry point for a request-response process.
        """
        for key in initkwargs:
            if key in cls.http_method_names:
                raise TypeError("You tried to pass in the %s method name as a "
                                "keyword argument to %s(). Don't do that."
                                % (key, cls.__name__))
            if not hasattr(cls, key):
                raise TypeError("%s() received an invalid keyword %r. as_view "
                                "only accepts arguments that are already "
                                "attributes of the class." % (cls.__name__, key))

        def view(request, *args, **kwargs):
            self = cls(**initkwargs)
            if hasattr(self, 'get') and not hasattr(self, 'head'):
                self.head = self.get
            self.request = request
            self.args = args
            self.kwargs = kwargs
            return self.dispatch(request, *args, **kwargs)

dispatch方法：

def dispatch(self, request, *args, **kwargs):
        # Try to dispatch to the right method; if a method doesn't exist,
        # defer to the error handler. Also defer to the error handler if the
        # request method isn't on the approved list.
        if request.method.lower() in self.http_method_names:
            handler = getattr(self, request.method.lower(), self.http_method_not_allowed)
        else:
            handler = self.http_method_not_allowed
        return handler(request, *args, **kwargs)

dispatch方法中根据http请求的method得到handler的值(get,post...),接着调用handler方法，如果是get请求，则调用的是get方法。get方法定义在BaseListView中：

class BaseListView(MultipleObjectMixin, View):
    """
    A base view for displaying a list of objects.
    """
    def get(self, request, *args, **kwargs):
        self.object_list = self.get_queryset()
        allow_empty = self.get_allow_empty()

        if not allow_empty:
            # When pagination is enabled and object_list is a queryset,
            # it's better to do a cheap query than to load the unpaginated
            # queryset in memory.
            if (self.get_paginate_by(self.object_list) is not None
                    and hasattr(self.object_list, 'exists')):
                is_empty = not self.object_list.exists()
            else:
                is_empty = len(self.object_list) == 0
            if is_empty:
                raise Http404(_("Empty list and '%(class_name)s.allow_empty' is False.")
                        % {'class_name': self.__class__.__name__})
        context = self.get_context_data()
        return self.render_to_response(context)

get_queryset、get_context_data在父类中的定义：

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.
        """
        if self.queryset is not None:
            queryset = self.queryset
            if isinstance(queryset, QuerySet):
                queryset = queryset.all()
        elif self.model is not None:
            queryset = self.model._default_manager.all()
        else:
            raise ImproperlyConfigured(
                "%(cls)s is missing a QuerySet. Define "
                "%(cls)s.model, %(cls)s.queryset, or override "
                "%(cls)s.get_queryset()." % {
                    'cls': self.__class__.__name__
                }
            )
        ordering = self.get_ordering()
        if ordering:
            if isinstance(ordering, six.string_types):
                ordering = (ordering,)
            queryset = queryset.order_by(*ordering)

        return queryset

        def get_context_object_name(self, object_list):
        """
        Get the name of the item to be used in the context.
        """
        if self.context_object_name:
            return self.context_object_name
        elif hasattr(object_list, 'model'):
            return '%s_list' % object_list.model._meta.model_name
        else:
            return None

        def get_context_data(self, **kwargs):
            """
            Get the context for this view.
            """
            queryset = kwargs.pop('object_list', self.object_list)
            page_size = self.get_paginate_by(queryset)
            context_object_name = self.get_context_object_name(queryset)
            if page_size:
                paginator, page, queryset, is_paginated = self.paginate_queryset(queryset, page_size)
                context = {
                    'paginator': paginator,
                    'page_obj': page,
                    'is_paginated': is_paginated,
                    'object_list': queryset
                }
            else:
                context = {
                    'paginator': None,
                    'page_obj': None,
                    'is_paginated': False,
                    'object_list': queryset
                }
            if context_object_name is not None:
                context[context_object_name] = queryset
            context.update(kwargs)
            return super(MultipleObjectMixin, self).get_context_data(**context)

当我们自定义的视图函数IndexView中重写get_context_data时，可将需传递到template的数据赋值给kwargs变量，最终数据会加入到context上下文中：

if context_object_name is not None:
        context[context_object_name] = queryset
        context.update(kwargs)

最后回到BaseListView类的get方法，调用了self.render_to_response(context)进行响应输出。