Shows how to update single Participants Database dynamic field triggered by a cron

pdb-dynamicfield-cron-updater2.php

<?php
/**
 * Plugin Name: PDB Dynamic Field Cron Updater Version 2
 * Description: updates a dynamic field automatically on a WP cron
 * Version: 2.0
 */

class PDb_Dynamicfield_Cron_Updater2
{
  
  /**
   * @param string name of the cron hook
   */
  private $hook = 'xnau_dynfield_update';
  
  /**
   * @param string name of the field to update
   */
  private $fieldname = 'age';
  
  /**
   * sets up the cron and actions
   */
  public function __construct()
  {
    // use this function to reset the cron
    // useful if you need to change the time it runs
    // remember to comment it out again after
    //$this->unschedule();
    
    // this sets up the method that is called when our cron runs
    add_action( $this->hook, [$this,'dynamic_db_field_update'] );
    
    /*
     *  this sets the daily cron time to 2pm
     * 
     *  IMPORTANT: normally, the WP cron is run when someone visits the site, 
     *  therefore if your site is not getting much traffic, the cron probably 
     *  won't run on time.
     * 
     *  There are many examples of how to set up the WP cron to run without 
     *  needing the site visit to trigger it, for example:
     *  https://www.siteground.com/tutorials/wordpress/real-cron-job/
     */
    $time_of_day = strtotime('2024-02-07 14:00:00');
    
    if ( ! wp_next_scheduled( $this->hook ) )
    {
      // this sets up the WP cron to trigger our action daily at the time set above
      wp_schedule_event( $time_of_day, 'daily', $this->hook );
    }
  }
  
  /**
   * update a dynamic db field value
   * 
   * this will process an update for a dynamic db field for all records
   * 
   * @return int number of records updated
   */
  public function dynamic_db_field_update()
  {
    do_action( 'pdb-dynamic_db_field_update_all', $this->fieldname, [] );
  }
  
  /**
   * unschedules the cron
   */
  private function unschedule()
  {
    $timestamp = wp_next_scheduled( $this->hook );
    wp_unschedule_event( $timestamp, $this->hook );
  }
}

new PDb_Dynamicfield_Cron_Updater2();

This requires Participants Database Version 2.5.7 or later to work.

This is to be installed as a plugin. You should set the name of the field that you want to update on line 19.

This plugin uses a background process to update all records, so it won't time out of there are a large number of records to process.