Setting Up cron within wordpress

Using standard recurrence values

Standard recurrence values are ‘hourly’, ‘daily’ and ‘twicedaily’.

//******************************************************************************
//******************************************************************************
//********** REGISTER / DE-REGISTER OUR CRON FUNCTIONS WITH WORDPRESS **********
//******************************************************************************
//******************************************************************************
//***** ACTIVATE *****
function my_cron_events_activate() {

  //Deactive first to ensure there won't be repeated events
  my_cron_events_deactivate();

  $Result = wp_schedule_event( time(), 'hourly', 'my_cron_main_event' );  //<<<Namespace only needed if outside of the current namespace



  /*
  if (is_wp_error($Result))
    echo "wp_schedule_event error: " . $Result->get_error_message();
  else if ($Result === True)
    echo "wp_schedule_event success";
  else
    echo "wp_schedule_event something went wrong";
  */
}

//***** DEACTIVATE *****
function my_cron_events_deactivate() {
    wp_clear_scheduled_hook('my_cron_main_event');

  //<<<Namespace only needed if outside of the current namespace

}

Using your own recurrence values

If you want something different from the standard recurrence values you can add the below to define them:

  //Using in your activate function:
  $Result = wp_schedule_event( time(), '5min', 'my_cron_main_event' );



//*************************************************
//***** CREATE OUR OWN CUSTOM SCHEDULE VALUES *****
//*************************************************
add_filter('cron_schedules','my_cron_schedules');    //<<<Change my_cron_schedules to a unique name (can't be shared by plugins or themes).
//add_filter('cron_schedules','\MyNamespaceName\my_cron_schedules');
function my_cron_schedules($schedules)
{
  //Add our custom schedule times here (1 or more)
  if(!isset($schedules["5min"]))
  {
      $schedules["5min"] = array(
          'interval' => 5*60,
          'display' => __('Once every 5 minutes'));
  }
  
  /*
  if(!isset($schedules["30min"]))
  {
      $schedules["30min"] = array(
          'interval' => 30*60,
          'display' => __('Once every 30 minutes'));
  }
  */
  
  return $schedules;
}

Configuring WordPress to use your setup

Run this once to setup with the new configuration

  //Recreate all events
  my_cron_events_activate();



  //Delete all events
  my_cron_events_deactivate();

Using with a plugin

Use the wp_schedule_event() with your plugin activation hook register_activation_hook().

Ensure you also use your plugins register_deactivation_hook() to clear the scheduled event as deactivating a plugin doesn’t do it.

Add a cron schedule task to your server to call the wp cron

//    */5 * * * * wget -q -O - https://mydomainame.uk/wp-cron.php?doing_wp_cron

Your cron function

//***********************************
//***********************************
//********** CRON FUNCTION **********
//***********************************
//***********************************
add_action( 'my_cron_main_event',  'my_cron_main_event' );    //<<<Change my_cron_main_event to a unique action name (can't be shared by plugins or themes).
//add_action( 'my_cron_main_event',  '\MyNamespaceName\my_cron_main_event' );
function my_cron_main_event()
{


}

Testing / Debugging

Run just your cron fucntion from code

Your cron function is created as an action, so you can trigger it to run from your own code using

do_action( 'my_cron_main_event' );

Run all wp cron functions

You can do this from a browser using:
https://mydomainname.com/wp-cron.php?doing_wp_cron

Remember though that wp will only trigger your function at the time interval you set for it, regardless of how often you trigger it