How to submit a button automatically after every scheduled hours?

Question

How to submit a button automatically after every scheduled hours ? I tried some JavaScript but all failed.

What I am doing?

• I am trying to fetch product categories from an external API

Why I want this to be fetched every scheduled time ?

• so that if someone not clicks manually, then also it will fetch after scheduled time, say any time or after every 8 hours

My codes:

    <?php
    /*
    Add menu page and button to fetch productcategories
    */
    function add_productcategories_menu_page()
    {
        add_menu_page(
            'Fetch productcategories',
            'Fetch productcategories',
            'manage_options',
            'productcategories',
            'productcategories_menu_page'
        );
    }
    add_action('admin_menu', 'add_productcategories_menu_page');
    
    function productcategories_menu_page()
    {
        ?>
        <div class="wrap">
            <h1>productcategories</h1>
            <form method="post" action="">
                <?php wp_nonce_field('fetch_productcategories_nonce', 'fetch_productcategories_nonce'); ?>
                <input type="submit" name="fetch_productcategories" value="Fetch productcategories" class="button button-primary">
            </form>
        </div>
        <?php
    }
    
    /*
    Get product Categories from API
    */
    function import_productcategories() {
        $url = '';
        $response = wp_remote_get( $url );
        $data = wp_remote_retrieve_body( $response );
        $json = json_decode( $data );
        if ( ! empty( $json ) ) {
            $existing_productcategories = get_terms( 'productcategories', array( 'hide_empty' => false ) );
            foreach ( $existing_productcategories as $existing_productcategorie ) {
                $found = false;
                foreach ( $json as $category ) {
                    if ( $category->productCategoryNameFi === $existing_productcategorie->productCategoryNameFi ) {
                        $found = true;
                        break;
                    }
                }
                if ( ! $found ) {
                    wp_delete_term( $existing_productcategorie->term_id, 'productcategories' );
                }
            }
            foreach ( $json as $category ) {
                $term = term_exists( $category->productCategoryNameFi, 'productcategories' );
                if ( $term === 0 || $term === null ) {
                    wp_insert_term( $category->productCategoryNameFi, 'productcategories', array(
                        'slug' => sanitize_title( $category->productCategoryNameFi )
                    ) );
                }
            }
        }
    }
    
    function fetch_productcategories_handler()
    {
        if (isset($_POST['fetch_productcategories']) && wp_verify_nonce($_POST['fetch_productcategories_nonce'], 'fetch_productcategories_nonce')) {
            import_productcategories();
            echo '<div class="updated"><p>productcategories fetched successfully!</p></div>';
        }
    }
    add_action('admin_init', 'fetch_productcategories_handler');

?>

I tried

<script>
        setInterval(function() {
            document.getElementById('fetch-form').submit();
        }, 60000); // Submit the form every 1 minute (60,000 milliseconds)
    </script>

and

add_action('wp_loaded', function() {
    $interval = 60; // 1 minute
    wp_schedule_event(time(), 'minutes', 'fetch_webcategories', array($interval));
});

function fetch_webcategories() {
    update_web_categories_terms();
}

Answer 1

You were on the right track with the second try. Put this is functions.php, or wherever:

if (!wp_next_scheduled('fetch_webcategories_hook')) {
    wp_schedule_event( time(), 'hourly', 'fetch_webcategories_hook' );
}
add_action ( 'fetch_webcategories_hook', 'fetch_webcategories' );

It's not quite a real hourly schedule because somebody has to visit the site to trigger it, so if you have VERY low traffic it might not run. Any time the site loads, it checks to see if it's time to do it, so if you get anything from 1 visitor an hour to a constant flood of traffic, it will run once an hour. Crawlers will trigger it, so if it's a public site, it should run at least occasionally. You could also leave a page, any page, up on a browser on a computer that doesn't go to sleep with a meta refresh tag:

<meta http-equiv="refresh" content="3600">

If you want to be really sure, you could set up monitoring. I do it with Rackspace because that's where my cloud servers are, but a quick google search turned up this site: https://uptimerobot.com/ which looks like it would do the job.

WP Crontrol is an excellent plugin for dealing with wordpress cron stuff. https://wordpress.org/plugins/wp-crontrol/