Multi Select fields via the API show with null, when not filled with empty string

[BastianHammer]

Issue

When I use the JSON API (and in some constellation of the import as well - still digging there for details) to create a record with a multi select field, I need to add the field like so into my payload:

"field_name": "",

otherwise, a null is displayed in the UI on edit and a list item dot on detail view:

It seems like a bug, that if I don't add the field into my payload, there is a null and cumbersome UI / manual correction work required. But with an empty string, all is good.

Possible Fix

If the key-value pair for a multi select field isn't in the payload, the standard behaviour should probably be to initialize it with an empty string, instead of null in the UI ( ^^ in the DB).

Steps to Reproduce the Issue

1. POST a payload without a key-value pair for a multi select field via JSON API

Context

No response

Version

8.10.1

What browser are you currently using?

Other

Browser Version

No response

Environment Information

MariaDB, PHP8.4

Operating System and Version

Ubuntu 24

[johnM2401]

Hey!

Thank you for getting in touch with this.

I've given this a try on the latest release and I've not been able to replicate, I'm afraid

I've sent the following request via the API, creating a new record and just supplying the Name value:

{
 "data": {
      "type": "Accounts",
      "attributes": {
        "name": "Api"
      }
  }
}

But my Multiselect field stays empty / no "null":

Am I perhaps missing something?

Does your dropdown list have anything special about it? (ie: a default Value / an "Empty" first value / etc)
Does the API request need to contain anything special?

Thank you again for your time!