Closes #12135: Prevent the deletion of interfaces with children

docs/models/dcim/interface.md

@@ -77,6 +77,9 @@ If selected, this component will be treated as if a cable has been connected.
 
 Virtual interfaces can be bound to a physical parent interface. This is helpful for modeling virtual interfaces which employ encapsulation on a physical interface, such as an 802.1Q VLAN-tagged subinterface.
 
+!!! note
+    An interface with one or more child interfaces assigned cannot be deleted until all its child interfaces have been deleted or reassigned.
+
 ### Bridged Interface
 
 Interfaces can be bridged to other interfaces on a device in two manners: symmetric or grouped.

docs/models/virtualization/vminterface.md

@@ -16,6 +16,9 @@ The interface's name. Must be unique to the assigned VM.
 
 Identifies the parent interface of a subinterface (e.g. used to employ encapsulation).
 
+!!! note
+    An interface with one or more child interfaces assigned cannot be deleted until all its child interfaces have been deleted or reassigned.
+
 ### Bridged Interface
 
 An interface on the same VM with which this interface is bridged.

netbox/dcim/migrations/0182_protect_child_interfaces.py

@@ -0,0 +1,19 @@
+# Generated by Django 4.2.6 on 2023-10-20 11:48
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('dcim', '0181_rename_device_role_device_role'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='interface',
+            name='parent',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.RESTRICT, related_name='child_interfaces', to='dcim.interface'),
+        ),
+    ]

netbox/dcim/models/device_components.py

@@ -537,7 +537,7 @@ class BaseInterface(models.Model):
     )
     parent = models.ForeignKey(
         to='self',
-        on_delete=models.SET_NULL,
+        on_delete=models.RESTRICT,
         related_name='child_interfaces',
         null=True,
         blank=True,

netbox/netbox/views/generic/bulk_views.py

@@ -7,7 +7,7 @@
 from django.contrib.contenttypes.models import ContentType
 from django.core.exceptions import FieldDoesNotExist, ObjectDoesNotExist, ValidationError
 from django.db import transaction, IntegrityError
-from django.db.models import ManyToManyField, ProtectedError
+from django.db.models import ManyToManyField, ProtectedError, RestrictedError
 from django.db.models.fields.reverse_related import ManyToManyRel
 from django.forms import HiddenInput, ModelMultipleChoiceField, MultipleHiddenInput
 from django.http import HttpResponse
@@ -804,8 +804,8 @@ def post(self, request, **kwargs):
                             obj.snapshot()
                         obj.delete()
 
-                except ProtectedError as e:
-                    logger.info("Caught ProtectedError while attempting to delete objects")
+                except (ProtectedError, RestrictedError) as e:
+                    logger.info(f"Caught {type(e)} while attempting to delete objects")
                     handle_protectederror(queryset, request, e)
                     return redirect(self.get_return_url(request))
 

netbox/netbox/views/generic/object_views.py

@@ -3,7 +3,7 @@
 
 from django.contrib import messages
 from django.db import transaction
-from django.db.models import ProtectedError
+from django.db.models import ProtectedError, RestrictedError
 from django.shortcuts import redirect, render
 from django.urls import reverse
 from django.utils.html import escape
@@ -374,8 +374,8 @@ def post(self, request, *args, **kwargs):
             try:
                 obj.delete()
 
-            except ProtectedError as e:
-                logger.info("Caught ProtectedError while attempting to delete object")
+            except (ProtectedError, RestrictedError) as e:
+                logger.info(f"Caught {type(e)} while attempting to delete objects")
                 handle_protectederror([obj], request, e)
                 return redirect(obj.get_absolute_url())
 

netbox/utilities/error_handlers.py

@@ -1,16 +1,28 @@
 from django.contrib import messages
+from django.db.models import ProtectedError, RestrictedError
 from django.utils.html import escape
 from django.utils.safestring import mark_safe
+from django.utils.translation import gettext_lazy as _
 
 
 def handle_protectederror(obj_list, request, e):
     """
-    Generate a user-friendly error message in response to a ProtectedError exception.
+    Generate a user-friendly error message in response to a ProtectedError or RestrictedError exception.
     """
-    protected_objects = list(e.protected_objects)
-    protected_count = len(protected_objects) if len(protected_objects) <= 50 else 'More than 50'
-    err_message = f"Unable to delete <strong>{', '.join(str(obj) for obj in obj_list)}</strong>. " \
-                  f"{protected_count} dependent objects were found: "
+    if type(e) is ProtectedError:
+        protected_objects = list(e.protected_objects)
+    elif type(e) is RestrictedError:
+        protected_objects = list(e.restricted_objects)
+    else:
+        raise e
+
+    # Formulate the error message
+    err_message = _(
+        "Unable to delete <strong>{objects}</strong>. {count} dependent objects were found: ".format(
+            objects=', '.join(str(obj) for obj in obj_list),
+            count=len(protected_objects) if len(protected_objects) <= 50 else _('More than 50')
+        )
+    )
 
     # Append dependent objects to error message
     dependent_objects = []

netbox/virtualization/migrations/0037_protect_child_interfaces.py

@@ -0,0 +1,19 @@
+# Generated by Django 4.2.6 on 2023-10-20 11:48
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('virtualization', '0036_virtualmachine_config_template'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='vminterface',
+            name='parent',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.RESTRICT, related_name='child_interfaces', to='virtualization.vminterface'),
+        ),
+    ]