Using WordPress ‘pre_schedule_event’ PHP filter

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The ‘pre_schedule_event’ WordPress PHP filter schedules a recurring event by attaching a hook that gets triggered by WordPress at the specified interval.

The action occurs when someone visits your WordPress site if the scheduled time has passed.

Usage

To schedule a recurring event, use the wp_schedule_event() function with the following parameters:

wp_schedule_event( $timestamp, $recurrence, $hook, $args = array(), $wp_error = false );

Parameters

  • $timestamp (int): Required. Unix timestamp (UTC) for when to next run the event.
  • $recurrence (string): Required. How often the event should subsequently recur. See wp_get_schedules() for accepted values.
  • $hook (string): Required. Action hook to execute when the event is run.
  • $args (array): Optional. Array containing arguments to pass to the hook’s callback function. Each value in the array is passed to the callback as an individual parameter. The array keys are ignored. Default: array()
  • $wp_error (bool): Optional. Whether to return a WP_Error on failure. Default: false

Examples

Schedule a daily backup

In this scenario, we want to schedule a daily backup of our WordPress site.

function my_daily_backup() {
    // Your backup logic here
}

add_action('my_daily_backup_hook', 'my_daily_backup');

if (!wp_next_scheduled('my_daily_backup_hook')) {
    wp_schedule_event(time(), 'daily', 'my_daily_backup_hook');
}

This code schedules a daily backup by adding an action named my_daily_backup_hook. It first checks if the event is already scheduled using wp_next_scheduled(). If not, it schedules the event using wp_schedule_event() with a ‘daily’ recurrence.

Schedule an hourly email notification

In this scenario, we want to send an email notification to the administrator every hour.

function hourly_email_notification() {
    // Your email sending logic here
}

add_action('hourly_email_notification_hook', 'hourly_email_notification');

if (!wp_next_scheduled('hourly_email_notification_hook')) {
    wp_schedule_event(time(), 'hourly', 'hourly_email_notification_hook');
}

This code schedules an hourly email notification by adding an action named hourly_email_notification_hook. It first checks if the event is already scheduled using wp_next_scheduled(). If not, it schedules the event using wp_schedule_event() with an ‘hourly’ recurrence.

Schedule a twice daily database optimization

In this scenario, we want to optimize our WordPress database twice daily.

function optimize_database() {
    // Your database optimization logic here
}

add_action('optimize_database_hook', 'optimize_database');

if (!wp_next_scheduled('optimize_database_hook')) {
    wp_schedule_event(time(), 'twicedaily', 'optimize_database_hook');
}

This code schedules a twice daily database optimization by adding an action named optimize_database_hook. It first checks if the event is already scheduled using wp_next_scheduled(). If not, it schedules the event using wp_schedule_event() with a ‘twicedaily’ recurrence.

Schedule a custom interval event

In this scenario, we want to schedule an event to run every 30 minutes.

function add_custom_cron_schedule($schedules) {
    $schedules['every_30_minutes'] = array(
        'interval' => 30 * MINUTE_IN_SECONDS,
        'display' => 'Every 30 minutes'
    );
    return $schedules;
}
add_filter('cron_schedules', 'add_custom_cron_schedule');
function run_every_30_minutes() { // Your logic for the event here }
add_action('run_every_30_minutes_hook', 'run_every_30_minutes');
if (!wp_next_scheduled('run_every_30_minutes_hook')) { 
wp_schedule_event(time(), 'every_30_minutes', 'run_every_30_minutes_hook'); 
}

This code schedules an event to run every 30 minutes by first adding a custom cron schedule named ‘every_30_minutes’ using the `add_custom_cron_schedule()` function and the `cron_schedules` filter. Then, it adds an action named `run_every_30_minutes_hook`. It checks if the event is already scheduled using `wp_next_scheduled()`. If not, it schedules the event using `wp_schedule_event()` with the ‘every_30_minutes’ recurrence.

Schedule a weekly user report generation

function add_weekly_cron_schedule($schedules) {
    $schedules['weekly'] = array(
        'interval' => 7 * DAY_IN_SECONDS,
        'display' => 'Once a week'
    );
    return $schedules;
}

add_filter('cron_schedules', 'add_weekly_cron_schedule');

function generate_user_report() {
    // Your user report generation logic here
}

add_action('generate_user_report_hook', 'generate_user_report');

if (!wp_next_scheduled('generate_user_report_hook')) {
    $next_week = strtotime('next Monday');
    wp_schedule_event($next_week, 'weekly', 'generate_user_report_hook');
} 

This code schedules a weekly user report generation by first adding a custom cron schedule named ‘weekly’ using the add_weekly_cron_schedule() function and the cron_schedules filter. Then, it adds an action named generate_user_report_hook. It checks if the event is already scheduled using wp_next_scheduled(). If not, it schedules the event using wp_schedule_event() with the ‘weekly’ recurrence, starting from the next Monday.