Decouple viewset mixins from model mixins[Draft / POC]

rules/contrib/rest_framework.py

@@ -1,7 +1,9 @@
 from django.core.exceptions import ImproperlyConfigured, PermissionDenied
 
+from ..viewsets import BaseAutoPermissionMixin
 
-class AutoPermissionViewSetMixin:
+
+class AutoPermissionViewSetMixin(BaseAutoPermissionMixin):
     """
     Enforces object-level permissions in ``rest_framework.viewsets.ViewSet``,
     deriving the permission type from the particular action to be performed..
@@ -70,6 +72,7 @@ def initial(self, *args, **kwargs):
             obj = self.get_object()
 
         # Finally, check permission
-        perm = self.get_queryset().model.get_perm(perm_type)
+        model = self.get_queryset().model
+        perm = self.get_permission_for_model(model, perm_type)
         if not self.request.user.has_perm(perm, obj):
             raise PermissionDenied

rules/contrib/views.py

@@ -12,6 +12,8 @@
 # versions before 1.9. For usage help see Django's docs for 1.9 or later.
 from django.views.generic.edit import BaseCreateView
 
+from ..viewsets import BaseAutoPermissionMixin
+
 LoginRequiredMixin = mixins.LoginRequiredMixin
 UserPassesTestMixin = mixins.UserPassesTestMixin
 
@@ -47,7 +49,7 @@ def has_permission(self):
         return self.request.user.has_perms(perms, obj)
 
 
-class AutoPermissionRequiredMixin(PermissionRequiredMixin):
+class AutoPermissionRequiredMixin(PermissionRequiredMixin, BaseAutoPermissionMixin):
     """
     An extended variant of PermissionRequiredMixin which automatically determines
     the permission to check based on the type of view it's used with.
@@ -119,7 +121,7 @@ def get_permission_required(self):
             model = getattr(self, "model", None)
             if model is None:
                 model = self.get_queryset().model
-            perms.append(model.get_perm(perm_type))
+            perms.append(self.get_permission_for_model(model, perm_type))
 
         # If additional permissions have been defined, consider them as well
         if self.permission_required is not None:

rules/viewsets.py

@@ -0,0 +1,21 @@
+# All auto permission mixins (both for DRF and Django views)
+# inherit from this mixin.
+class BaseAutoPermissionMixin:
+    def get_perm(self, model, perm_type):
+        return "%s.%s_%s" % (model._meta.app_label, perm_type, model._meta.model_name)
+
+    def get_permission_for_model(self, model, perm_type):
+
+        # Attempt to use model mixin. If model mixin is not available,
+        # default to standard convetion of this project (or allow
+        # overriding `get_perm` through a custom Mixin)
+        try:
+            use_model_mixin_method = callable(model.get_perm)
+        except AttributeError:
+            use_model_mixin_method = False
+
+        if use_model_mixin_method:
+            perm = model.get_perm(perm_type)
+        else:
+            perm = self.get_perm(model, perm_type)
+        return perm