Adds a meta box to one or more screens.

$id string Required

Meta box ID (used in the 'id' attribute for the meta box).

$title string Required

Title of the meta box.

$callback callable Required

Function that fills the box with the desired content.
The function should echo its output.

$screen string|array|WP_Screen Optional

The screen or screens on which to show the box (such as a post type, 'link', or 'comment'). Accepts a single screen ID, WP_Screen object, or array of screen IDs. Default is the current screen. If you have used add_menu_page() or add_submenu_page() to create a new screen (and hence screen_id), make sure your menu slug conforms to the limits of sanitize_key() otherwise the 'screen' menu may not correctly render on your page.

Default: null

$context string Optional

The context within the screen where the box should display. Available contexts vary from screen to screen. Post edit screen contexts include 'normal', 'side', and 'advanced'. Comments screen contexts include 'normal' and 'side'. Menus meta boxes (accordion sections) all use the 'side' context. Global default is 'advanced'.

Default: 'advanced'

$priority string Optional

The priority within the context where the box should show.
Accepts 'high', 'core', 'default', or 'low'. Default 'default'.

Default: 'default'

$callback_args array Optional

Data that should be set as the $args property of the box array (which is the second parameter passed to your callback).

Default: null

File: wp-admin/includes/template.php. View all references

function add_meta_box( $id, $title, $callback, $screen = null, $context = 'advanced', $priority = 'default', $callback_args = null ) {
	global $wp_meta_boxes;

	if ( empty( $screen ) ) {
		$screen = get_current_screen();
	} elseif ( is_string( $screen ) ) {
		$screen = convert_to_screen( $screen );
	} elseif ( is_array( $screen ) ) {
		foreach ( $screen as $single_screen ) {
			add_meta_box( $id, $title, $callback, $single_screen, $context, $priority, $callback_args );
		}
	}

	if ( ! isset( $screen->id ) ) {
		return;
	}

	$page = $screen->id;

	if ( ! isset( $wp_meta_boxes ) ) {
		$wp_meta_boxes = array();
	}
	if ( ! isset( $wp_meta_boxes[ $page ] ) ) {
		$wp_meta_boxes[ $page ] = array();
	}
	if ( ! isset( $wp_meta_boxes[ $page ][ $context ] ) ) {
		$wp_meta_boxes[ $page ][ $context ] = array();
	}

	foreach ( array_keys( $wp_meta_boxes[ $page ] ) as $a_context ) {
		foreach ( array( 'high', 'core', 'default', 'low' ) as $a_priority ) {
			if ( ! isset( $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ] ) ) {
				continue;
			}

			// If a core box was previously removed, don't add.
			if ( ( 'core' === $priority || 'sorted' === $priority )
				&& false === $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ]
			) {
				return;
			}

			// If a core box was previously added by a plugin, don't add.
			if ( 'core' === $priority ) {
				/*
				 * If the box was added with default priority, give it core priority
				 * to maintain sort order.
				 */
				if ( 'default' === $a_priority ) {
					$wp_meta_boxes[ $page ][ $a_context ]['core'][ $id ] = $wp_meta_boxes[ $page ][ $a_context ]['default'][ $id ];
					unset( $wp_meta_boxes[ $page ][ $a_context ]['default'][ $id ] );
				}
				return;
			}

			// If no priority given and ID already present, use existing priority.
			if ( empty( $priority ) ) {
				$priority = $a_priority;
				/*
				 * Else, if we're adding to the sorted priority, we don't know the title
				 * or callback. Grab them from the previously added context/priority.
				 */
			} elseif ( 'sorted' === $priority ) {
				$title         = $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ]['title'];
				$callback      = $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ]['callback'];
				$callback_args = $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ]['args'];
			}

			// An ID can be in only one priority and one context.
			if ( $priority !== $a_priority || $context !== $a_context ) {
				unset( $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ] );
			}
		}
	}

	if ( empty( $priority ) ) {
		$priority = 'low';
	}

	if ( ! isset( $wp_meta_boxes[ $page ][ $context ][ $priority ] ) ) {
		$wp_meta_boxes[ $page ][ $context ][ $priority ] = array();
	}

	$wp_meta_boxes[ $page ][ $context ][ $priority ][ $id ] = array(
		'id'       => $id,
		'title'    => $title,
		'callback' => $callback,
		'args'     => $callback_args,
	);
}