Django RestFramework源码剖析(2)———Viwe是自带分页的

#路径：/rest_framework/generics.pyclass GenericAPIView(views.APIView):    """    Base class for all other generic views.    """    ...........    # Pagination settings    paginate_by = api_settings.PAGINATE_BY    paginate_by_param = api_settings.PAGINATE_BY_PARAM    max_paginate_by = api_settings.MAX_PAGINATE_BY    pagination_serializer_class = api_settings.DEFAULT_PAGINATION_SERIALIZER_CLASS    page_kwarg = 'page'    # The filter backend classes to use for queryset filtering    filter_backends = api_settings.DEFAULT_FILTER_BACKENDS    # The following attributes may be subject to change,    # and should be considered private API.    model_serializer_class = api_settings.DEFAULT_MODEL_SERIALIZER_CLASS    paginator_class = Paginator    def get_pagination_serializer(self, page):        """        Return a serializer instance to use with paginated data.        """        class SerializerClass(self.pagination_serializer_class):            class Meta:                object_serializer_class = self.get_serializer_class()        pagination_serializer_class = SerializerClass        context = self.get_serializer_context()        return pagination_serializer_class(instance=page, context=context)    def paginate_queryset(self, queryset, page_size=None):        """        Paginate a queryset if required, either returning a page object,        or `None` if pagination is not configured for this view.        """        deprecated_style = False        if page_size is not None:            warnings.warn('The `page_size` parameter to `paginate_queryset()` '                          'is due to be deprecated. '                          'Note that the return style of this method is also '                          'changed, and will simply return a page object '                          'when called without a `page_size` argument.',                          PendingDeprecationWarning, stacklevel=2)            deprecated_style = True        else:            # Determine the required page size.            # If pagination is not configured, simply return None.            page_size = self.get_paginate_by()                             #在这里查询分页个数            if not page_size:                return None        if not self.allow_empty:            warnings.warn(                'The `allow_empty` parameter is due to be deprecated. '                'To use `allow_empty=False` style behavior, You should override '                '`get_queryset()` and explicitly raise a 404 on empty querysets.',                PendingDeprecationWarning, stacklevel=2            )        paginator = self.paginator_class(queryset, page_size,                                         allow_empty_first_page=self.allow_empty)        page_kwarg = self.kwargs.get(self.page_kwarg)        page_query_param = self.request.QUERY_PARAMS.get(self.page_kwarg)        page = page_kwarg or page_query_param or 1        try:            page_number = paginator.validate_number(page)        except InvalidPage:            if page == 'last':                page_number = paginator.num_pages            else:                raise Http404(_("Page is not 'last', nor can it be converted to an int."))        try:            page = paginator.page(page_number)        except InvalidPage as e:            raise Http404(_('Invalid page (%(page_number)s): %(message)s') % {                                'page_number': page_number,                                'message': str(e)            })        if deprecated_style:            return (paginator, page, page.object_list, page.has_other_pages())        return page    ########################    ### The following methods provide default implementations    ### that you may want to override for more complex cases.    def get_paginate_by(self, queryset=None):        """        Return the size of pages to use with pagination.        If `PAGINATE_BY_PARAM` is set it will attempt to get the page size        from a named query parameter in the url, eg. ?page_size=100        Otherwise defaults to using `self.paginate_by`.        """        if queryset is not None:            warnings.warn('The `queryset` parameter to `get_paginate_by()` '                          'is due to be deprecated.',                          PendingDeprecationWarning, stacklevel=2)        if self.paginate_by_param:            try:                return strict_positive_int(                    self.request.QUERY_PARAMS[self.paginate_by_param],                    cutoff=self.max_paginate_by                )            except (KeyError, ValueError):                pass        return self.paginate_by    ..........

路径：/rest_framework/mixins.pyclass ListModelMixin(object):    def list(self, request, *args, **kwargs):        self.object_list = self.filter_queryset(self.get_queryset())        # Default is to allow empty querysets.  This can be altered by setting        # `.allow_empty = False`, to raise 404 errors on empty querysets.        if not self.allow_empty and not self.object_list:            warnings.warn(                'The `allow_empty` parameter is due to be deprecated. '                'To use `allow_empty=False` style behavior, You should override '                '`get_queryset()` and explicitly raise a 404 on empty querysets.',                PendingDeprecationWarning            )            class_name = self.__class__.__name__            error_msg = self.empty_error % {'class_name': class_name}            raise Http404(error_msg)        # Switch between paginated or standard style responses        page = self.paginate_queryset(self.object_list)        if page is not None:            serializer = self.get_pagination_serializer(page)        else:            serializer = self.get_serializer(self.object_list, many=True)        return Response(serializer.data)

这里可以得知，在ListAPIView之中调用了paginate_queryset(), 观察paginate_queryset()之中是使用了分页的。
而分页的设置就是在self.paginate_by中设置，这个值是在setting文件及之中。这里贴出一个配置文件的例子：

REST_FRAMEWORK = {    ......    'PAGINATE_BY': 8,    'PAGINATE_BY_PARAM': 'count',    'FILTER_BACKEND': 'rest_framework.filters.DjangoFilterBackend',    'DATETIME_FORMAT': ("%Y-%m-%d %H:%M:%S"),}