Incorrect handling of null value in custom fields

[karlism]

NetBox version

v2.10.6

Python version

3.6

Steps to Reproduce

1. Have existing custom field with empty value (in my case it's dcim > device custom field)
2. Update from NetBox 2.9.11 to 2.10.6
3. Add new device and leave this custom field empty while creating it
4. Value of this custom field will be "" (empty string) instead of null

Expected Behavior

Value of empty custom fields should be null

Observed Behavior

Value of empty custom fields is "" (empty string). Devices that have been added prior to update to NetBox 2.10.6, still have proper value null for empty custom fields.

[karlism]

All following operations are performed in NetBox 2.10.6.

To demonstrate this bit better, existing device that has been created prior to upgrade to NetBox 2.10.6:

    "custom_fields": {
        "ansible_groups": "esxi_vms,virtual,letsencrypt,awx_nodes",
        "ansible_python_interpreter": null,
        "environment": "development"
    },

New device that has been added in NetBox 2.10.6 (no changes have been made to custom fields):

    "custom_fields": {
        "ansible_groups": "esxi_vms,virtual,feproxy",
        "ansible_python_interpreter": "",
        "environment": "development"
    },

Now I will create new custom field with default null value:

Lets check previous device again:

    "custom_fields": {
        "ansible_groups": "esxi_vms,virtual,feproxy",
        "ansible_python_interpreter": "",
        "environment": "development",
        "test": null
    },

Now add new device again:

    "custom_fields": {
        "ansible_groups": "some,groups,here",
        "ansible_python_interpreter": "",
        "environment": "development",
        "test": ""
    },

[karlism]

Just upgraded to NetBox 2.11.1 and behavior is same, I think this is also related to this issue: #6217

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. NetBox is governed by a small group of core maintainers which means not all opened issues may receive direct feedback. Please see our contributing guide.

[karlism]

I guess that this issue is also related: #6686