wp-includes/ms-site.php:906Checks whether a site is initialized.
$site_idint|WP_SiteboolOne hook fires while wp_is_site_initialized() runs, in this order:
Filters the check for whether a site is initialized before the database is accessed.
function wp_is_site_initialized( $site_id ) { global $wpdb; if ( is_object( $site_id ) ) { $site_id = $site_id->blog_id; } $site_id = (int) $site_id; /** * Filters the check for whether a site is initialized before the database is accessed. * * Returning a non-null value will effectively short-circuit the function, returning * that value instead. * * @since 5.1.0 * * @param bool|null $pre The value to return instead. Default null * to continue with the check. * @param int $site_id The site ID that is being checked. */ $pre = apply_filters( 'pre_wp_is_site_initialized', null, $site_id ); if ( null !== $pre ) { return (bool) $pre; } $switch = false; if ( get_current_blog_id() !== $site_id ) { $switch = true; remove_action( 'switch_blog', 'wp_switch_roles_and_user', 1 ); switch_to_blog( $site_id ); } $suppress = $wpdb->suppress_errors(); $result = (bool) $wpdb->get_results( "DESCRIBE {$wpdb->posts}" ); $wpdb->suppress_errors( $suppress ); if ( $switch ) { restore_current_blog(); add_action( 'switch_blog', 'wp_switch_roles_and_user', 1, 2 ); } return $result;}Introduced in 5.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/ms-site.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.