fix save of content type

Author: arthanson

netbox_custom_objects/models.py

@@ -14,7 +14,8 @@
 from django.db import connection, IntegrityError, models, transaction
 from django.db.models import Q
 from django.db.models.functions import Lower
-from django.db.models.signals import pre_delete
+from django.db.models.signals import pre_delete, post_save
+from django.dispatch import receiver
 from django.urls import reverse
 from django.utils.translation import gettext_lazy as _
 from core.signals import handle_deleted_object
@@ -671,17 +672,8 @@ def save(self, *args, **kwargs):
         needs_db_create = self._state.adding
 
         super().save(*args, **kwargs)
-        if needs_db_create:
-            # If creating a new object, get or create the ObjectType
-            content_type_name = self.get_table_model_name(self.id).lower()
-            ct, created = ObjectType.objects.get_or_create(
-                app_label=APP_LABEL,
-                model=content_type_name
-            )
-            # Force a refresh to ensure it's available in the current transaction
-            # ct.refresh_from_db()
-            self.object_type = ct
 
+        if needs_db_create:
             self.create_model()
         else:
             # Clear the model cache when the CustomObjectType is modified
@@ -694,7 +686,7 @@ def delete(self, *args, **kwargs):
         model = self.get_model()
 
         # Delete all CustomObjectTypeFields that reference this CustomObjectType
-        for field in CustomObjectTypeField.objects.filter(related_object_type=self.content_type):
+        for field in CustomObjectTypeField.objects.filter(related_object_type=self.object_type):
             field.delete()
 
         object_type = ObjectType.objects.get_for_model(model)
@@ -710,6 +702,19 @@ def delete(self, *args, **kwargs):
         pre_delete.connect(handle_deleted_object)
 
 
+@receiver(post_save, sender=CustomObjectType)
+def custom_object_type_post_save_handler(sender, instance, created, **kwargs):
+    if created:
+        # If creating a new object, get or create the ObjectType
+        content_type_name = instance.get_table_model_name(instance.id).lower()
+        ct, created = ObjectType.objects.get_or_create(
+            app_label=APP_LABEL,
+            model=content_type_name
+        )
+        instance.object_type = ct
+        instance.save()
+
+
 class CustomObjectTypeField(CloningMixin, ExportTemplatesMixin, ChangeLoggedModel):
     custom_object_type = models.ForeignKey(
         CustomObjectType, on_delete=models.CASCADE, related_name="fields"
@@ -1118,6 +1123,83 @@ def clean(self):
                     }
                 )
 
+        # Check for recursion in object and multiobject fields
+        if (self.type in (
+            CustomFieldTypeChoices.TYPE_OBJECT,
+            CustomFieldTypeChoices.TYPE_MULTIOBJECT,
+        ) and self.related_object_type_id and 
+            self.related_object_type.app_label == APP_LABEL):
+            self._check_recursion()
+
+    def _check_recursion(self):
+        """
+        Check for circular references in object and multiobject fields.
+        Raises ValidationError if recursion is detected.
+        """
+        # Check if this field points to the same custom object type (self-referential)
+        print(f"related_object_type_id: {self.related_object_type_id}, custom_object_type.object_type_id: {self.custom_object_type.object_type_id}")
+        breakpoint()
+        if self.related_object_type_id == self.custom_object_type.object_type_id:
+            return  # Self-referential fields are allowed
+
+        # Get the related custom object type directly from the object_type relationship
+        try:
+            related_custom_object_type = CustomObjectType.objects.get(object_type=self.related_object_type)
+        except CustomObjectType.DoesNotExist:
+            return  # Not a custom object type, no recursion possible
+
+        # Check for circular references by traversing the dependency chain
+        visited = {self.custom_object_type.id}
+        if self._has_circular_reference(related_custom_object_type, visited):
+            raise ValidationError(
+                {
+                    "related_object_type": _(
+                        "Circular reference detected. This field would create a circular dependency "
+                        "between custom object types."
+                    )
+                }
+            )
+
+    def _has_circular_reference(self, custom_object_type, visited):
+        """
+        Recursively check if there's a circular reference by following the dependency chain.
+        
+        Args:
+            custom_object_type: The CustomObjectType object to check
+            visited: Set of custom object type IDs already visited in this traversal
+            
+        Returns:
+            bool: True if a circular reference is detected, False otherwise
+        """
+        # If we've already visited this type, we have a cycle
+        if custom_object_type.id in visited:
+            return True
+
+        # Add this type to visited set
+        visited.add(custom_object_type.id)
+        
+        # Check all object and multiobject fields in this custom object type
+        for field in custom_object_type.fields.filter(
+            type__in=[
+                CustomFieldTypeChoices.TYPE_OBJECT,
+                CustomFieldTypeChoices.TYPE_MULTIOBJECT,
+            ],
+            related_object_type__isnull=False,
+            related_object_type__app_label=APP_LABEL
+        ):
+
+            # Get the related custom object type directly from the object_type relationship
+            try:
+                next_custom_object_type = CustomObjectType.objects.get(object_type=field.related_object_type)
+            except CustomObjectType.DoesNotExist:
+                continue
+            
+            # Recursively check this dependency
+            if self._has_circular_reference(next_custom_object_type, visited):
+                return True
+
+        return False
+
     def serialize(self, value):
         """
         Prepare a value for storage as JSON data.

netbox_custom_objects/views.py

@@ -203,7 +203,7 @@ def _get_dependent_objects(self, obj):
 
         # Find CustomObjectTypeFields that reference this CustomObjectType
         referencing_fields = CustomObjectTypeField.objects.filter(
-            related_object_type=obj.content_type
+            related_object_type=obj.object_type
         )
 
         # Add the CustomObjectTypeFields that reference this CustomObjectType