Demonstrates a Participants Database plugin that sets the "strict user searches" mode according to the presence of a wildcard in the search term

pdb-auto-search-mode.php

<?php

/**
 * Plugin Name: PDB Auto Search Mode
 * Description: switches the "strict user search" mode off if there is a wildcard in the search term
 * Author: xnau webdesign
 * Version: 1.2
 */
class pdb_auto_search_mode {
  
  /**
   * @var string strict mode setting value
   */
  private $mode = 1;
  
  /**
   * @var int the input we are checking
   */
  private $input;

  /**
   * 
   */
  public function __construct()
  {
    add_action( 'pdb-shortcode_set', [$this, 'set_search_mode'] );
    add_filter( 'pdb-strict_search_setting_value', [ $this, 'set_mode' ] );
  }

  /**
   * 
   * @param PDb_Shortcode $shortcode
   * @return array
   */
  public function set_search_mode( $shortcode )
  {
    // check for the GET search variables
    $this->input = array_key_exists( 'search_field', $_GET ) && array_key_exists( 'value', $_GET ) ? INPUT_GET : INPUT_POST;
    
    // check if the submission is a list search
    if ( $this->is_pdb_search() )
    {
      // get the search term
      $term = filter_input( $this->input, 'value', FILTER_DEFAULT, Participants_Db::string_sanitize() );
     
      // get the setting value according to whether there is a wildcard present or not
      $this->mode = strpos( $term, '*' ) === false ? 1 : 0;
    }
  }
  
  /**
   * sets the mode setting
   * 
   * @param string $setting
   * @return string
   */
  public function set_mode( $setting )
  {
    return $this->mode;
  }
  
  /**
   * check to see if the current submission is a Participants Database search
   * 
   * @return bool
   */
  private function is_pdb_search()
  {
    if ( $this->input === INPUT_POST )
    {
      return filter_input( $this->input, 'action', FILTER_DEFAULT, Participants_Db::string_sanitize() ) === 'pdb_list_filter' && array_key_exists( 'search_field', $_POST ) && array_key_exists( 'value', $_POST );
    }
    else {
      return array_key_exists( 'search_field', $_GET ) && array_key_exists( 'value', $_GET );
    }
  }
}

new pdb_auto_search_mode();

Update to also automatically set the strict mode with searches made with a URL