我使用Django Rest Framework的CursorPagination，我想在单个视图集中覆盖默认的page_size(10)和ordering('timestamp')。我该怎么办？
我尝试过使用视图集，但未成功：
from rest_framework.pagination import CursorPagination
class ListAPIView(ListAPIView):
queryset = Cake.objects.all()
permission_classes = [AllowAny]
serializer_class = ListSerializer
pagination_class = CursorPagination
filter_backends = (OrderingFilter, DjangoFilterBackend)
filter_class = CakeListFilter
filterset_fields = ('cake_type', 'user__username')
ordering = '-date'
page_size = 5
答案 0 :(得分：1)
您可以创建一个继承自CursorPagination类的新类，以便像这样设置自定义page_size和/或max_page_size：
class CustomPageSizeCursorPagination(CursorPagination):
page_size = 5
max_page_size = 100
然后将此类用作您的视图集的pagination_class字段
另一个选择是编写一个自定义分页器类，该类从视图集中获取页面大小。例如：
class PageSizeInViewSetCursorPagination(CursorPagination):
def get_page_size(self, request, viewset_page_size):
if self.page_size_query_param:
try:
return _positive_int(
request.query_params[self.page_size_query_param],
strict=True,
cutoff=self.max_page_size
)
except (KeyError, ValueError):
pass
return viewset_page_size or self.page_size
def paginate_queryset(self, queryset, request, view=None):
# Get the page_size from the viewset and then decide which page_size to use
viewset_page_size = getattr(view, 'page_size', None)
page_size = self.get_page_size(request, viewset_page_size)
# What follows is copy/paste of the code from CursorPagination paginate_queryset method
if not self.page_size:
return None
self.base_url = request.build_absolute_uri()
self.ordering = self.get_ordering(request, queryset, view)
self.cursor = self.decode_cursor(request)
if self.cursor is None:
(offset, reverse, current_position) = (0, False, None)
else:
(offset, reverse, current_position) = self.cursor
# Cursor pagination always enforces an ordering.
if reverse:
queryset = queryset.order_by(*_reverse_ordering(self.ordering))
else:
queryset = queryset.order_by(*self.ordering)
# If we have a cursor with a fixed position then filter by that.
if current_position is not None:
order = self.ordering[0]
is_reversed = order.startswith('-')
order_attr = order.lstrip('-')
# Test for: (cursor reversed) XOR (queryset reversed)
if self.cursor.reverse != is_reversed:
kwargs = {order_attr + '__lt': current_position}
else:
kwargs = {order_attr + '__gt': current_position}
queryset = queryset.filter(**kwargs)
# If we have an offset cursor then offset the entire page by that amount.
# We also always fetch an extra item in order to determine if there is a
# page following on from this one.
results = list(queryset[offset:offset + self.page_size + 1])
self.page = list(results[:self.page_size])
# Determine the position of the final item following the page.
if len(results) > len(self.page):
has_following_position = True
following_position = self._get_position_from_instance(results[-1], self.ordering)
else:
has_following_position = False
following_position = None
# If we have a reverse queryset, then the query ordering was in reverse
# so we need to reverse the items again before returning them to the user.
if reverse:
self.page = list(reversed(self.page))
if reverse:
# Determine next and previous positions for reverse cursors.
self.has_next = (current_position is not None) or (offset > 0)
self.has_previous = has_following_position
if self.has_next:
self.next_position = current_position
if self.has_previous:
self.previous_position = following_position
else:
# Determine next and previous positions for forward cursors.
self.has_next = has_following_position
self.has_previous = (current_position is not None) or (offset > 0)
if self.has_next:
self.next_position = following_position
if self.has_previous:
self.previous_position = current_position
# Display page controls in the browsable API if there is more
# than one page.
if (self.has_previous or self.has_next) and self.template is not None:
self.display_page_controls = True
return self.page
请注意，在以上示例中，page_size中的request始终优先于您在代码中设置的内容。然后viewset_page_size是第二行，最后是page_size类中的聋人Pagination。
答案 1 :(得分：1)
这是自定义的分页类，扩展了CursorPagination。它检查在视图集中定义的ordering和page_size属性，如果存在则使用它们。如果不是，则退回到分页类本身中定义的原始设置。
class NewsCursorPaginator(CursorPagination):
ordering = 'title'
page_size = 5
# get_page_size do not have view attribute, so we have our custom one
def get_custom_page_size(self, request, view):
viewset_page_size = getattr(view, 'page_size', None)
if viewset_page_size:
self.page_size = viewset_page_size
return super(NewsCursorPaginator, self).get_page_size(request)
def get_ordering(self, request, queryset, view):
viewset_ordering = getattr(view, 'ordering', None)
if viewset_ordering:
self.ordering = viewset_ordering
return super(NewsCursorPaginator, self).get_ordering(request, queryset, view)
def paginate_queryset(self, queryset, request, view=None):
self.page_size = self.get_custom_page_size(request, view)
return super(NewsCursorPaginator, self).paginate_queryset(queryset, request, view)
答案 2 :(得分：0)
此实现将“ limit”（page_size）作为可选的querystring参数。
class CursorPagination(pagination.CursorPagination):
page_size = settings.REST_FRAMEWORK["PAGE_SIZE"]
def get_custom_page_size(self, request, view):
try:
self.page_size = int(request.GET.get("limit"))
except (ValueError, TypeError):
pass
return super().get_page_size(request)
def paginate_queryset(self, queryset, request, view=None):
self.page_size = self.get_custom_page_size(request, view)
return super().paginate_queryset(queryset, request, view)