Fixes Distance Rate Shipping not updating during checkout when address fields (like city or postcode) change within the same state. Adds JS to trigger recalculation and clears transients server-side to force fresh rate calculation.

force-distance-rate-shipping-recalc.php

/**
 * Force recalculation of shipping rates when address fields change during checkout
 * Fixes issue with Distance Rate Shipping not updating for address changes within the same state
 */
function wooninja_force_shipping_recalculation() {
    if ( ! is_checkout() ) {
        return;
    }
    ?>
    <script type="text/javascript">
    jQuery(function($) {
        // These are the fields we want to watch for changes
        var addressFields = [
            '#shipping_address_1',
            '#shipping_address_2',
            '#shipping_city',
            '#shipping_postcode',
            '#shipping_state',
            '#shipping_country'
        ];

        // Watch for changes in any address field
        $(document.body).on('change', addressFields.join(', '), function() {
            console.log('Address field changed, updating checkout...');
            
            // Clear the distance rate shipping cache by adding a timestamp to the post data
            $(document.body).on('update_checkout', function(event, args) {
                if (args && args.update_shipping_method) {
                    // Add current timestamp to force cache refresh
                    args.force_distance_recalc = new Date().getTime();
                }
            });
            
            // Trigger update checkout
            $(document.body).trigger('update_checkout');
        });
    });
    </script>
    <?php
}
add_action('wp_footer', 'wooninja_force_shipping_recalculation');

/**
 * Clear distance rate shipping cache when checkout is updated
 */
function wooninja_clear_distance_rate_cache($post_data) {
    global $wpdb;
    
    // Parse the post data
    parse_str($post_data, $data);
    
    // Check if our marker is present, or if shipping address fields changed
    $address_fields_changed = isset($data['force_distance_recalc']) || 
                             isset($data['shipping_address_1']) || 
                             isset($data['shipping_city']) || 
                             isset($data['shipping_postcode']);
    
    if ($address_fields_changed) {
        // Delete all transients related to distance rate shipping
        $wpdb->query("DELETE FROM {$wpdb->options} WHERE option_name LIKE '%_transient_distance_rate_shipping_%'");
        $wpdb->query("DELETE FROM {$wpdb->options} WHERE option_name LIKE '%_transient_timeout_distance_rate_shipping_%'");
    }
}
add_action('woocommerce_checkout_update_order_review', 'wooninja_clear_distance_rate_cache', 10, 1);