There's no need for the custom mixin now

apps/rp/api/mixins.py

-from django_fsm import has_transition_perm, can_proceed
-from rest_framework.decorators import action
-from rest_framework.exceptions import PermissionDenied
-from rest_framework.response import Response
-
-import inspect
-
-
-def get_transition_viewset_method(model, transition_name):
-    @action(methods=['post'], detail=True)
-    def inner_func(self, request, pk=None, *args, **kwargs):
-        object = self.get_object()
-        transition_method = getattr(object, transition_name)
-
-        if not can_proceed(transition_method):
-            raise PermissionDenied
-
-        if not has_transition_perm(transition_method, request.user):
-            raise PermissionDenied
-
-        if 'by' in inspect.getargspec(transition_method).args:
-            transition_method(*args, by=request.user, **kwargs)
-        else:
-            transition_method(*args, **kwargs)
-
-        if self.save_after_transition:
-            object.save()
-
-        serializer = self.get_serializer(object)
-        return Response(serializer.data)
-
-    return inner_func
-
-
-def get_viewset_transition_actions_mixin(model):
-    """
-    Automatically generate methods for Django REST Framework from transition
-    rules.
-    """
-    instance = model()
-
-    class Mixin(object):
-        save_after_transition = True
-
-    transitions = instance.get_all_status_transitions()
-    transition_names = set(x.name for x in transitions)
-    for transition_name in transition_names:
-        setattr(Mixin, transition_name,
-                get_transition_viewset_method(model, transition_name))
-
-    return Mixin