Vlan group: Removing scope fails via api because scope_type does not allow nulls

[amhn]

NetBox version

v3.3.6 && master

Python version

3.10

Steps to Reproduce

1. Create site
2. Create Vlan Group with scope
3. Send {"scope_type": null, "scope_id": null} to /api/ipam/vlan-groups/ method PATCH

Expected Behavior

Scope is unset.

Observed Behavior

An error is returned:

{"scope_type":["This field may not be null."]}

[amhn]

The following diff allows removing the scope via API:

diff --git a/netbox/ipam/api/serializers.py b/netbox/ipam/api/serializers.py
index fa8b563e9..eff39a418 100644
--- a/netbox/ipam/api/serializers.py
+++ b/netbox/ipam/api/serializers.py
@@ -175,6 +175,7 @@ class VLANGroupSerializer(NetBoxModelSerializer):
         queryset=ContentType.objects.filter(
             model__in=VLANGROUP_SCOPE_TYPES
         ),
+        allow_null=True,
         required=False,
         default=None
     )

[amhn]

Same problem and fix with the time_zone attribute of site:

diff --git a/netbox/dcim/api/serializers.py b/netbox/dcim/api/serializers.py
index 897ee4ca3..cb1edfe1f 100644
--- a/netbox/dcim/api/serializers.py
+++ b/netbox/dcim/api/serializers.py
@@ -130,7 +130,7 @@ class SiteSerializer(NetBoxModelSerializer):
     region = NestedRegionSerializer(required=False, allow_null=True)
     group = NestedSiteGroupSerializer(required=False, allow_null=True)
     tenant = NestedTenantSerializer(required=False, allow_null=True)
-    time_zone = TimeZoneSerializerField(required=False)
+    time_zone = TimeZoneSerializerField(required=False, allow_null=True)
     asns = SerializedPKRelatedField(
         queryset=ASN.objects.all(),
         serializer=NestedASNSerializer,

[jeremystretch]

Same problem and fix with the time_zone attribute of site:

Please open a separate bug report for this.