Closes #10851: New staging mechanism (#10890)

* WIP

* Convert checkout() context manager to a class

* Misc cleanup

* Drop unique constraint from Change model

* Extend staging tests

* Misc cleanup

* Incorporate M2M changes

* Don't cancel wipe out creation records when an object is deleted

* Rename Change to StagedChange

* Add documentation for change staging

netbox/utilities/utils.py

@@ -6,7 +6,8 @@ from decimal import Decimal
 from itertools import count, groupby
 
 import bleach
-from django.core.serializers import serialize
+from django.contrib.contenttypes.models import ContentType
+from django.core import serializers
 from django.db.models import Count, OuterRef, Subquery
 from django.db.models.functions import Coalesce
 from django.http import QueryDict
@@ -135,14 +136,14 @@ def count_related(model, field):
     return Coalesce(subquery, 0)
 
 
-def serialize_object(obj, extra=None):
+def serialize_object(obj, resolve_tags=True, extra=None):
     """
     Return a generic JSON representation of an object using Django's built-in serializer. (This is used for things like
     change logging, not the REST API.) Optionally include a dictionary to supplement the object data. A list of keys
     can be provided to exclude them from the returned dictionary. Private fields (prefaced with an underscore) are
     implicitly excluded.
     """
-    json_str = serialize('json', [obj])
+    json_str = serializers.serialize('json', [obj])
     data = json.loads(json_str)[0]['fields']
 
     # Exclude any MPTTModel fields
@@ -154,8 +155,9 @@ def serialize_object(obj, extra=None):
     if hasattr(obj, 'custom_field_data'):
         data['custom_fields'] = data.pop('custom_field_data')
 
-    # Include any tags. Check for tags cached on the instance; fall back to using the manager.
-    if is_taggable(obj):
+    # Resolve any assigned tags to their names. Check for tags cached on the instance;
+    # fall back to using the manager.
+    if resolve_tags and is_taggable(obj):
         tags = getattr(obj, '_tags', None) or obj.tags.all()
         data['tags'] = sorted([tag.name for tag in tags])
 
@@ -172,6 +174,24 @@ def serialize_object(obj, extra=None):
     return data
 
 
+def deserialize_object(model, fields, pk=None):
+    """
+    Instantiate an object from the given model and field data. Functions as
+    the complement to serialize_object().
+    """
+    content_type = ContentType.objects.get_for_model(model)
+    if 'custom_fields' in fields:
+        fields['custom_field_data'] = fields.pop('custom_fields')
+    data = {
+        'model': '.'.join(content_type.natural_key()),
+        'pk': pk,
+        'fields': fields,
+    }
+    instance = list(serializers.deserialize('python', [data]))[0]
+
+    return instance
+
+
 def dict_to_filter_params(d, prefix=''):
     """
     Translate a dictionary of attributes to a nested set of parameters suitable for QuerySet filtering. For example: