Plugin to enable the exclusive option feature in the admin record edit in Participants Database

pdb-admin-exclusive-options.php

<?php

/**
 * Plugin Name: PDB Admin Exclusive Options
 * Description: enables exclusive options in the admin record editor
 * Version: 1.1
 */

class pdb_admin_exclusive_options {
  
  /**
   * sets up the filters
   */
  public function __construct()
  {
    if ( is_admin() )
    {
      add_action( 'participants-database_initialized', [$this, 'setup_field_filters'], 5 );
    }
  }
  
  /**
   * sets up the list of fields with exclusive options
   */
  public function setup_field_filters()
  {
    foreach( Participants_Db::$fields as $field_def )
    {
      /** @var \PDb_Form_Field_Def $field_def */
      if ( $field_def->is_value_set() && array_key_exists( 'exclusive', $field_def->attributes ) )
      {
        // for every field that has the exclusive attribute, we add the filter that esclused the alread-chosen options
        add_filter( 'pdb-' . $field_def->name() . '_selector_option_attribute_list', [$this,'set_disabled_atts'], 10, 4 );
      }
    }
  }
  
  /**
   * handles setting the disabled attributes
   * 
   * 
   * 
   * @param array $attributes
   * @param string $fieldname
   * @param string $value
   * @return array of attributes
   */
  public function set_disabled_atts(  $attributes, $fieldname, $value, $record_id  )
  {
    if ( empty( $record_id ) ) // make sure we have the record ID
    {
      $record_id = filter_input( INPUT_GET, 'id', FILTER_SANITIZE_NUMBER_INT );
    }
    
    return \PDb_fields\exclusive_options::filter_handler( $attributes, $fieldname, $value, $record_id );
  }
}

new pdb_admin_exclusive_options();

This code is installed as a plugin How to Install a WordPress Plugin from a Gist

Version 1.1 fixes a bug where the previously selected value would be deselected when the record was updated.