Closes #13427: Public model registration (#14152)

* Initial work on #13427

* Clarify documentation

* Reference public models registry when populating models for ConfigTemplate context

netbox/core/models/__init__.py

@@ -1,3 +1,4 @@
+from .contenttypes import *
 from .data import *
 from .files import *
 from .jobs import *

netbox/core/models/contenttypes.py

@@ -0,0 +1,32 @@
+from django.contrib.contenttypes.models import ContentType as ContentType_, ContentTypeManager as ContentTypeManager_
+from django.db.models import Q
+
+from netbox.registry import registry
+
+__all__ = (
+    'ContentType',
+    'ContentTypeManager',
+)
+
+
+class ContentTypeManager(ContentTypeManager_):
+
+    def public(self):
+        """
+        Filter the base queryset to return only ContentTypes corresponding to "public" models; those which are listed
+        in registry['models'] and intended for reference by other objects.
+        """
+        q = Q()
+        for app_label, models in registry['models'].items():
+            q |= Q(app_label=app_label, model__in=models)
+        return self.get_queryset().filter(q)
+
+
+class ContentType(ContentType_):
+    """
+    Wrap Django's native ContentType model to use our custom manager.
+    """
+    objects = ContentTypeManager()
+
+    class Meta:
+        proxy = True

netbox/core/models/data.py

@@ -378,6 +378,8 @@ class AutoSyncRecord(models.Model):
         fk_field='object_id'
     )
 
+    _netbox_private = True
+
     class Meta:
         constraints = (
             models.UniqueConstraint(

netbox/core/models/files.py

@@ -44,6 +44,7 @@ class ManagedFile(SyncedDataMixin, models.Model):
     )
 
     objects = RestrictedQuerySet.as_manager()
+    _netbox_private = True
 
     class Meta:
         ordering = ('file_root', 'file_path')