Custom fields default value on Objects from modules are not set

[Etibru]

Deployment Type

Self-hosted

Triage priority

N/A

NetBox Version

v4.1.4

Python Version

3.12

Steps to Reproduce

1. Create a required custom field and set a default value. Choose an object like DCIM > Interface.

{
    "id": 8,
    "display": "My cf",
    "object_types": [
        "dcim.interface"
    ],
    "type": {
        "value": "text",
        "label": "Text"
    },
    "related_object_type": null,
    "data_type": "string",
    "name": "My_CF",
    "label": "",
    "group_name": "",
    "description": "",
    "required": true,
    "unique": false,
    "search_weight": 1000,
    "filter_logic": {
        "value": "loose",
        "label": "Loose"
    },
    "ui_visible": {
        "value": "always",
        "label": "Always"
    },
    "ui_editable": {
        "value": "yes",
        "label": "Yes"
    },
    "is_cloneable": false,
    "default": "default_value",
    "related_object_filter": null,
    "weight": 100,
    "validation_minimum": null,
    "validation_maximum": null,
    "validation_regex": "",
    "choice_set": null,
    "comments": "",
}

2.Create a module type with a few interfaces.

3. Create a device, create a module bay on this device.
   

4. Connect a module with the module type
   

Now, we have the interfaces from the type module that have been added to the device.

And if we see an Interface:

We can see that the default value has not been set.

"custom_fields": {
"My_CF": null
},
Note that in devices with device_type, interface custom fields (for example) are set to the default value

Expected Behavior

We should have the default value and not null. on the same way as on a device type with interfaces, when the device is created, there will be the default value on the interfaces custom field.

Observed Behavior

Interfaces that are created when the module is connected to a device, the default values of custom fields are not set to their default values.

[Etibru]

I've had a quick look at where the SET default value is missing.

HERE, when a device is created and components added, the custom field value is set to default.

               # Set default values for any applicable custom fields
                if cf_defaults := CustomField.objects.get_defaults_for_model(model):
                    component.custom_field_data = cf_defaults
                component.save()

For module bay components, you'll need to add more or less the same resonance HERE.

Something like this :

                for component in create_instances:
                    if cf_defaults := CustomField.objects.get_defaults_for_model(component_model):
                        component.custom_field_data = cf_defaults
                    post_save.send(
                        sender=component_model,
                        instance=component,
                        created=True,
                        raw=False,
                        using='default',
                        update_fields=None
                    )

Maybe there's something better to do