python - 如何在 DRF 中组合/混合对象级别和用户级别权限？

Question

我目前正在开发一个 DRF 项目，其中管理员用户、教师用户和所有者用户应该能够访问对象详细信息 View 。基本上所有用户类型，除了那些不是对象所有者、教师或管理员用户的用户。我能够为每个权限实现单独的权限，但是当我需要在 View 上组合这些权限时，我遇到了障碍，因为在对象级别权限之前检查用户级别权限。因此，我不能使用 bool 操作数来组合它们，我必须为我的 View 编写这些丑陋的权限类。

我的问题是:

如何以更清晰的方式在详细信息 View 上实现这些权限，或者是否有更清晰的方式来获取结果？

正如您将看到的，我违反了 DRY，因为我有 IsAdminOrOwner 和 IsAdminOrTeacherOrOwner 烫发。您还会注意到，在我看来，我覆盖了 get_permissions() 以便为各个请求方法提供适当的权限类。欢迎对此和其他实现提出任何评论，我想要批评，以便我可以改进它。

以下是权限.py:

from rest_framework import permissions
from rest_framework.permissions import IsAdminUser

class IsOwner(permissions.BasePermission):

    def has_permission(self, request, view):
        return True

    def has_object_permission(self, request, view, obj):
        return request.user == obj

class IsTeacher(permissions.BasePermission):

    def has_permission(self, request, view):
        return request.user.groups.filter(
            name='teacher_group').exists()

class IsAdminOrOwner(permissions.BasePermission):

    def has_object_permission(self, *args):
        is_owner = IsOwner().has_object_permission(*args)

        #convert tuple to list
        new_args = list(args)
        #remove object for non-object permission args
        new_args.pop()
        is_admin = IsAdminUser().has_permission(*new_args)

        return is_owner or is_admin

class IsAdminOrTeacherOrOwner(permissions.BasePermission):

    def has_object_permission(self, *args):
        is_owner = IsOwner().has_object_permission(*args)

        #convert tuple to list
        new_args = list(args)
        #remove object for non-object permission args
        new_args.pop()
        is_admin = IsAdminUser().has_permission(*new_args)
        is_teacher = IsTeacher().has_permission(*new_args)

        return is_admin or is_teacher or is_owner

这是我的观点:

class UserRetrieveUpdateView(APIView):
    serializer_class = UserSerializer

    def get_permissions(self):
        #the = is essential, because with each view
        #it resets the permission classes
        #if we did not implement it, the permissions
        #would have added up incorrectly
        self.permission_classes = [IsAuthenticated]

        if self.request.method == 'GET':
            self.permission_classes.append(
                IsAdminOrTeacherOrOwner)

        elif self.request.method == 'PUT':
            self.permission_classes.append(IsOwner)

        return super().get_permissions()

    def get_object(self, pk):
        try:
            user = User.objects.get(pk=pk)
            self.check_object_permissions(self.request, user)
            return user
        except User.DoesNotExist:
            raise Http404

    def get(self, request, pk, format=None):
        user = self.get_object(pk)
        serializer = self.serializer_class(user)
        return Response(serializer.data, status.HTTP_200_OK)

    def put(self, request, pk, format=None):
        user = self.get_object(pk)
        #we use partial to update only certain values
        serializer = self.serializer_class(user,
            data=request.data, partial=True)

        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data,
                status.HTTP_200_OK)

        return Response(status=status.HTTP_400_BAD_REQUEST)

Answer 1

Permissions in DRF可以使用按位 OR 运算符进行组合。例如，您可以这样做:

permission_classes = (IsAdmin | IsOwner | IsTeacher)

这样，您就不必定义单独的类来组合它们。