Default values for custom_fields are ignored in API when custom_fields section is used

[antonvdl]

Deployment Type

Self-hosted

NetBox Version

v4.2.3

Python Version

3.12

Steps to Reproduce

1. Create multiple custom_fields with object type IPAM > Prefix

• primary_subnet, type: boolean, required: yes, default value: true
• ripe_admin, type: text, required: no, default value: "xxx-RIPE"
• ripe_tech, type: text, required:no
• ripe_netname, type: text, required: no

2. Create a new prefix using API without custom_fields
   { "prefix": "10.0.0.0/24", "status": "active", "description": "Test prefix", "vlan": "147", "is_pool": false, "tenant": 6 }
3. Create a new prefix using API with only "primary_subnet" as custom_field
   { "prefix": "10.0.0.0/24", "status": "active", "description": "Test prefix", "vlan": "147", "is_pool": false, "tenant": 6, "custom_fields": { "primary_subnet": true } }
4. Create a new prefix using API with only "ripe_netname" as custom_field
   { "prefix": "10.0.0.0/24", "status": "active", "description": "Test prefix", "vlan": "147", "is_pool": false, "tenant": 6, "custom_fields": { "ripe_netname": "test" } }

Expected Behavior

1. Custom fields are created
2. Prefix is created with default values for custom_fields primary_subnet and ripe_admin. Other custom_fields are null
3. Prefix is created with supplied value for custom_field primary_subnet, default value for ripe_admin. Other custom_fields are null
4. Prefix is created with default values for custom_fields primary_subnet and ripe_admin. ripe_netname gets the supplied value and ripe_tech remains null

Observed Behavior

As soon as a custom_fields section is available in the POST Body then the default values for all custom_fields are ignored.
When I do not send the custom_fields section at all then the default values are used correctly.

1. Custom fields are created (OK)
2. Prefix is created with default values for primary_subnet and ripe_admin (OK)
3. Prefix is created with primary_subnet set to true but other custom_fields are empty -> default value for ripe_admin is ignored
4. Prefix is not created because primary_subnet (required) is not supplied -> default value for primary_subnet is ignored

[atownson]

The same is also true for scripts that create instances of objects. Omitting the custom_field_data dict creates the object with the custom field default values as expected, but including the custom_field_data dict and omitting a required field does not set a value for the custom field.

You can deal with this in scripts like such (which might indicate how to solve this issue):

ip_address = IPAddress(
	address = '192.168.0.1/32'
)
ip_address.populate_custom_field_defaults()
ip_address.custom_field_data['my_custom_field'] = 'hard-coded value'
ip_address.full_clean()
ip_address.save()

[atownson]

I believe the issue is that the default values are not populated in CustomFieldsDataField.to_internal_value().

[atownson]

I can submit a PR for this.