gistfile1.txt

from rest_framework import (
    exceptions,
    permissions,
)

from addon_service.models import (
    ResourceReference,
    UserReference,
)
from app.authentication import authenticate_resource


class UserReferenceIsAuthenticatedBase(permissions.BasePermission):
    """
    A permission class that ensures the user_reference_iri in the session matches
    the iri of the user associated with the user.
    """

    def has_permission(self, request, view):
        user_reference_iri = request.session.get("user_reference_iri")
        referenced_user = self.get_referenced_user(request, view)
        return user_reference_iri == referenced_user.user

    def get_referenced_user(self, request):
        try:
            return UserReference.objects.get(
                user_uri=request.session.get("user_reference_iri")
            )
        except UserReference.DoesNotExist:
            raise exceptions.NotAuthenticated()


class BaseConfiguredStorageAddonPermission(UserReferenceIsAuthenticatedBase):
    """
    A permission class that ensures the resource_reference_iri in the session matches
    the iri of the user associated with the resource.
    """

    def get_referenced_user(self, request, view):
        if request.method == "POST" and request.data:
            resource = authenticate_resource(
                request=request,
                iri=request.data["authorized_resource"]["id"],
                required_permission="admin",
                create=True,
            )
            
            csa_with_this_resource =  resource.configured_storage_addons.filter(
                base_account__authorized_resource=resource
            )
            return csa_with_this_resource.get(owners__user_uri=request.session['user_reference_uri'])
        ... # other methods maybe class based