Introduce resolve_permission() utility function

netbox/users/models.py

@@ -12,6 +12,7 @@ from django.db.models.signals import post_save
 from django.dispatch import receiver
 from django.utils import timezone
 
+from utilities.permissions import resolve_permission
 from utilities.utils import flatten_dict
 
 
@@ -202,11 +203,9 @@ class ObjectPermissionManager(models.Manager):
         Compile all ObjectPermission attributes applicable to a specific combination of user, model, and action. Returns
         a dictionary that can be passed directly to .filter() on a QuerySet.
         """
-        app_label, codename = perm.split('.')
-        action, model_name = codename.split('_')
+        content_type, action = resolve_permission(perm)
         assert action in ['view', 'add', 'change', 'delete'], f"Invalid action: {action}"
 
-        content_type = ContentType.objects.get(app_label=app_label, model=model_name)
         qs = self.get_queryset().filter(
             Q(users=user) | Q(groups__user=user),
             model=content_type,

netbox/utilities/auth_backends.py

@@ -7,6 +7,7 @@ from django.contrib.contenttypes.models import ContentType
 from django.db.models import Q
 
 from users.models import ObjectPermission
+from utilities.permissions import resolve_permission
 
 
 class ObjectPermissionBackend(ModelBackend):
@@ -40,7 +41,6 @@ class ObjectPermissionBackend(ModelBackend):
         return user_obj._object_perm_cache
 
     def has_perm(self, user_obj, perm, obj=None):
-        # print(f'has_perm({perm})')
         app_label, codename = perm.split('.')
         action, model_name = codename.split('_')
 
@@ -120,10 +120,9 @@ class RemoteUserBackend(_RemoteUserBackend):
         permissions_list = []
         for permission_name in settings.REMOTE_AUTH_DEFAULT_PERMISSIONS:
             try:
-                app_label, codename = permission_name.split('.')
-                action, model_name = codename.split('_')
+                content_type, action = resolve_permission(permission_name)
                 user.object_permissions.create(**{
-                    'model': ContentType.objects.get(app_label=app_label, model=model_name),
+                    'model': content_type,
                     f'can_{action}': True
                 })
                 permissions_list.append(permission_name)

netbox/utilities/permissions.py

@@ -1,3 +1,6 @@
+from django.contrib.contenttypes.models import ContentType
+
+
 def get_permission_for_model(model, action):
     """
     Resolve the named permission for a given model (or instance) and action (e.g. view or add).
@@ -13,3 +16,20 @@ def get_permission_for_model(model, action):
         action,
         model._meta.model_name
     )
+
+
+def resolve_permission(name):
+    """
+    Given a permission name, return the relevant ContentType and action. For example, "dcim.view_site" returns
+    (Site, "view").
+
+    :param name: Permission name in the format <app>.<action>_<model>
+    """
+    app_label, codename = name.split('.')
+    action, model_name = codename.split('_')
+    try:
+        content_type = ContentType.objects.get(app_label=app_label, model=model_name)
+    except ContentType.DoesNotExist:
+        raise ValueError(f"Unknown app/model for {name}")
+
+    return content_type, action

netbox/utilities/testing/testcases.py

@@ -7,6 +7,7 @@ from django.urls import reverse, NoReverseMatch
 from rest_framework.test import APIClient
 
 from users.models import ObjectPermission, Token
+from utilities.permissions import resolve_permission
 from .utils import disable_warnings, post_data
 
 
@@ -32,11 +33,9 @@ class TestCase(_TestCase):
         Assign a set of permissions to the test user. Accepts permission names in the form <app>.<action>_<model>.
         """
         for name in names:
-            app_label, codename = name.split('.')
-            action, model_name = codename.split('_')
-
+            ct, action = resolve_permission(name)
             self.user.object_permissions.create(**{
-                'model': ContentType.objects.get(app_label=app_label, model=model_name),
+                'model': ct,
                 f'can_{action}': True
             })
 
@@ -45,11 +44,9 @@ class TestCase(_TestCase):
         Remove a set of permissions from the test user, if assigned.
         """
         for name in names:
-            app_label, codename = name.split('.')
-            action, model_name = codename.split('_')
-
+            ct, action = resolve_permission(name)
             self.user.object_permissions.filter(**{
-                'model': ContentType.objects.get(app_label=app_label, model=model_name),
+                'model': ct,
                 f'can_{action}': True
             }).delete()