将ListModelMixin与APIView结合使用以显示分页 [英] Combine ListModelMixin with APIView to show pagination

问题描述

我想在我的API中显示分页功能，并且我将APIView与多个序列化程序一起使用.
我知道用ListView显示分页非常容易.
我在某处看到可以组合使用ListModelMixin和APIView的方法，但是如果我的代码如下:

I want to show the pagination feature in my API and I am using APIView with multiple serializers.
I know it is very easy to show pagination with ListView.
I have seen somewhere that combining ListModelMixin and APIView works but if my code is as follows:

class ListModelMixin(object):
    def list(self, request, *args, **kwargs):
        queryset = self.filter_queryset(self.get_queryset())
        page = self.paginate_queryset(queryset)
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            return self.get_paginated_response(serializer.data)
        serializer = self.get_serializer(queryset, many=True)
        return Response(serilaizer.data)

class ItemsAPIView(APIView):
    permission_classes = (permissions.IsAuthenticated,)
    pagination_class = api_settings.DEFAULT_PAGINATION_CLASS

    def get(self, request, format=None):
        """
        Return a list of all devices of this user.
        """
        reply = {}
        try:
            products = BaseItem.objects.owned_items().filter(owner=request.user)
            reply['data'] = OwnedItemSerializer(products, many=True).data

            items = BaseItem.objects.dev_items().filter(owner=request.user)
            reply['data'].extend(ItemSerializer(items, many=True).data)

        except:
            reply['data'] = []
        return Response(reply, status.HTTP_200_OK)

如何合并它们以便获得分页结果?
预先感谢！

How can I combine them so I can get paginated results?
Thanks in advance!

推荐答案

首先，您当前正在做的事情过于复杂，没有理由.

First things first, what you are currently doing is too complex without reason.

为了实现可分页"查询集，最好使用简单的过滤器组合而不是模型方法来更改owned_items()和dev_items().通过示例进行澄清:

In order to achieve a "paginatable" queryset, it is preferred to change your owned_items() and dev_items() in simple filter combinations, rather than model methods. To clarify by example:

products = BaseItem.objects.filter(owner=request.user, owned=True)

代替

products = BaseItem.objects.owned_items().filter(owner=request.user)

这样，您可以生成一个更易于分页的单个查询集:

That way, you can produce a single queryset which will be easier to paginate:

user_items = BaseItem.objects.filter(
                 Q(owner=request.user, owned=True) |
                 Q(owner=request.user, dev=True)
             )

注释1:如果愿意，您可以进一步简化事情，但这超出了您的问题范围.值得深思，请查看以下内容:

Note 1: You can simplify things further if you like, but that gets out of scope of your question. As food for thought, check this out:

user_items =  BaseItem.objects.filter(owner=request.user).distinct()

注2::您应该对单个模型使用单个序列化程序，因为您所做的事情会增加复杂性而无益(高风险，低回报的情况)

Note 2: You should use a single serializer for a single model because what you are doing adds complexity without benefit (high risk-low reward situation)

具有以上提到并假定的条件:

With the above mentioned and assumed:

有一些方法可以在这里实现您想要的:

There are some ways to achieve what you want here:

1. 通过使用 GeneriAPIView 和 ListModelMixin ，您可以在一种具有自动分页的.list()方法的方法:

1. By utilizing GeneriAPIView and ListModelMixin you can refactor your class in such a way to have a .list() method with auto-pagination:

from rest_framework import mixins, generics

class ItemsAPIView(mixins.ListModelMixin, generics.GenericAPIView,):
    permission_classes = (permissions.IsAuthenticated,)
    pagination_class = api_settings.DEFAULT_PAGINATION_CLASS
    serializer_class = OwnedItemSerializer

    # You can define .get in here if you really need it.
    # You can also override .list to add specific functionality

如果您不想使用以上内容，并且希望保留您的APIView，则可以保留get方法并为其提供分页，如本

If you don't want to use the above, and you want to keep your APIView, then you can keep your get method and provide pagination for it as mentioned in this Q&A example:

class ItemsAPIView(APIView):
    permission_classes = (permissions.IsAuthenticated,)
    pagination_class = api_settings.DEFAULT_PAGINATION_CLASS
    serializer_class = MyNewUnifiedSerializerClass

    def get(self, request):
        user_items =  BaseItem.objects.filter(
                          owner=request.user
                      ).distinct()
        page = self.paginate_queryset(user_items)

        if page is not None:
            serializer = self.serializer_class(page, many=True)
            return self.get_paginated_response(serializer.data)

        serializer = self.get_serializer(user_items, many=True)
        return Response(serializer.data)

    # Now add the pagination handlers taken from 
    #  django-rest-framework/rest_framework/generics.py

    @property
    def paginator(self):
        """
        The paginator instance associated with the view, or `None`.
        """
        if not hasattr(self, '_paginator'):
            if self.pagination_class is None:
                self._paginator = None
            else:
                self._paginator = self.pagination_class()
            return self._paginator

     def paginate_queryset(self, queryset):
         """
         Return a single page of results, 
         or `None` if pagination is disabled.
         """
         if self.paginator is None:
             return None
         return self.paginator.paginate_queryset(
                    queryset, 
                    self.request, 
                    view=self
                )

     def get_paginated_response(self, data):
         """
         Return a paginated style `Response` object 
         for the given output data.
         """
         assert self.paginator is not None
         return self.paginator.get_paginated_response(data)

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