Describe the bug
The current implementation of the update statement in the extended Eloquent isn't suitable for the settings data model. Considering the example:

UPDATE announcement_settings SET setting_value = 
CASE WHEN setting_name='title' AND locale='en' THEN 'English Title' WHEN setting_name='title' AND locale='fr_CA' THEN 'French TItle' ELSE setting_value END
WHERE announcement_id = 16;

It doesn't allow to remove null values of already existing settings. Considering the example, if we already have a database record:

Then, trying to update with

$announcement->title = [
  'fr_FR' => Title in French modified
];
$announcement->save();

won't remove the title in English:

update - The EntityDAO behaviour is to remove values explicitly set to null, e.g.

$announcement->update(
  'title' => [
    'en' => null,
    'fr_FR' => 'Title in French modified'
  ],
)

Also, we need to insert new settings during update.
We have two places in the code, where the logic is implemented:

• Old DAO:

  pkp-lib/classes/db/DAO.php

  Line 432 in b4bb499

  public function updateDataObjectSettings(string $tableName, DataObject $dataObject, array $idArray)

• EntityDAO:

  pkp-lib/classes/core/EntityDAO.php

  Line 190 in b4bb499

  protected function _update(DataObject $object): void

@touhidurabir's proposal: https://github.com/pkp/pkp-lib/pull/10324/files#diff-4dcc09fe73d537128c17c4bbb260ad4ba24ccc0ecb8cdc7d0b47ebc7986e2cedR79-R129

What application are you using?
OJS, OMP or OPS main branch