(六) rest_framework 普通分页与加密分页

分页两类，一类是普通的分页，另外是加密的分页（页码加密而且只能跳转上页与下一页）
核心源代码：
results = list(queryset[offset:offset + self.page_size + 1])

普通分页：
from rest_framework.pagination import PageNumberPagination
对于指定的参数，可全局配置或者继承PageNumberPagination类进行重写配置

class AllAccounts(APIView):
    def get(self, request):
        accounts = AccountModel.objects.all()
        pg = PageNumberPagination()
        pg_data = pg.paginate_queryset(queryset=accounts,request=request,view=self)
        serializers = AccountSerializers(pg_data, many=True, context={'request': request})
        return pg.get_paginated_response(serializers.data)

对于加密翻页 CursorPagination
from rest_framework.pagination import CursorPagination

class MyCursorPagination(CursorPagination):
    cursor_query_param = 'cursor' # 翻页参数
    page_size = 2
    ordering = 'id' #默认是根据 -create 排序
    page_size_query_param = None

class AllAccounts(APIView):

    def get(self, request):
        accounts = AccountModel.objects.all()
        pg = MyCursorPagination()
        pg_data = pg.paginate_queryset(queryset=accounts,request=request,view=self)
        serializers = AccountSerializers(pg_data, many=True, context={'request': request})
        return pg.get_paginated_response(serializers.data)
"""
对于response，会携带上下翻页的页码
例如：
"next": "http://127.0.0.1:8000/api/accounts/?cursor=cD00",
"previous": "http://127.0.0.1:8000/api/accounts/?cursor=cj0xJnA9Mw%3D%3D",
"""

对于获取页码的get_page_size方法

def get_page_size(self, request):
        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
                )
                #query_params内部封装的 调用self._request.GET方法
            except (KeyError, ValueError):
                pass
        return self.page_size