Django REST Framework - Separate permissions per methods

问题

I am writing an API using Django REST Framework and I am wondering if can specify permissions per method when using class based views.

Reading the documentation I see that is quite easy to do if you are writing function based views, just using the @permission_classes decorator over the function of the views you want to protect with permissions. However, I don't see a way to do the same when using CBVs with the APIView class, because then I specify the permissions for the full class with the permission_classes attribute, but that will be applied then to all class methods (get, post, put...).

So, is it possible to have the API views written with CBVs and also specify different permissions for each method of a view class?

回答1:

Permissions are applied to the entire View class, but you can take into account aspects of the request (like the method such as GET or POST) in your authorization decision.

See the built-in IsAuthenticatedOrReadOnly as an example:

SAFE_METHODS = ['GET', 'HEAD', 'OPTIONS']

class IsAuthenticatedOrReadOnly(BasePermission):
    """
    The request is authenticated as a user, or is a read-only request.
    """

    def has_permission(self, request, view):
        if (request.method in SAFE_METHODS or
            request.user and
            request.user.is_authenticated()):
            return True
        return False

回答2:

I've come across the same problem when using CBV's, as i have fairly complex permissions logic depending on the request method.

The solution i came up with was to use the third party 'rest_condition' app listed at the bottom of this page

http://www.django-rest-framework.org/api-guide/permissions

https://github.com/caxap/rest_condition

I just split the permissions flow logic so that each branch will run, depending on the request method.

from rest_condition import And, Or, Not

class MyClassBasedView(APIView):

    permission_classes = [Or(And(IsReadOnlyRequest, IsAllowedRetrieveThis, IsAllowedRetrieveThat),
                             And(IsPostRequest, IsAllowedToCreateThis, ...),
                             And(IsPutPatchRequest, ...),
                             And(IsDeleteRequest, ...)]

So the 'Or' determines which branch of the permissions should run depending on the request method and the 'And' wraps the permissions relating to the accepted request method, so all must pass for permission to be granted. You can also mix 'Or', 'And' and 'Not' within each flow to create even more complex permissions.

The permission classes to run each branch simply look like this,

class IsReadyOnlyRequest(permissions.BasePermission):

    def has_permission(self, request, view):
        return request.method in permissions.SAFE_METHODS


class IsPostRequest(permissions.BasePermission):

    def has_permission(self, request, view):
        return request.method == "POST"


... #You get the idea

回答3:

I ran into this problem and really wanted to use the @permission_classes decorator to mark some custom view methods with specific permissions. I ended up coming up with a mixin:

class PermissionsPerMethodMixin(object):
    def get_permissions(self):
        """
        Allows overriding default permissions with @permission_classes
        """
        view = getattr(self, self.action)
        if hasattr(view, 'permission_classes'):
            return [permission_class() for permission_class in view.permission_classes]
        return super().get_permissions()

An example use case:

from rest_framework.decorators import action, permission_classes  # other imports elided

class MyViewset(PermissionsPerMethodMixin, viewsets.ModelViewSet):
    permission_classes = (IsAuthenticatedOrReadOnly,)  # used for default ViewSet endpoints
    queryset = MyModel.objects.all()
    serializer_class = MySerializer

    @action(detail=False, methods=['get'])
    @permission_classes((IsAuthenticated,))  # overrides IsAuthenticatedOrReadOnly
    def search(self, request):
        return do_search(request)  # ...

回答4:

I know this is an old question but I recently ran into the same problem and wanted to share my solution (since the accepted answer wasn't quite what I needed). @GDorn's answer put me on the right track, but it only works with ViewSets because of the self.action

I've solved it creating my own decorator:

def method_permission_classes(classes):
    def decorator(func):
        def decorated_func(self, *args, **kwargs):
            self.permission_classes = classes
            return func(self, *args, **kwargs)
        return decorated_func
    return decorator

Instead of setting the permission_classes property on the function, like the built-in decorator does, my decorator wraps the call and sets the permission classes on the view instance that is being called. This way, the normal get_permissions() doesn't need any changes, since that simply relies on self.permission_classes.

Example use case:

from rest_framework import views, permissions

class MyView(views.APIView):
    permission_classes = (permissions.IsAuthenticatedOrReadOnly,)  # used for default APIView endpoints
    queryset = MyModel.objects.all()
    serializer_class = MySerializer


    @method_permission_classes((permissions.IsAdminUser,))  # overrides IsAuthenticatedOrReadOnly
    def delete(self, request, id):
        instance = self.get_object()  # ...

Hope this helps someone running into the same problem!

来源：https://stackoverflow.com/questions/19773869/django-rest-framework-separate-permissions-per-methods