A HitchHackers guide through WordPress

Source code

function update_metadata_by_mid( $meta_type, $meta_id, $meta_value, $meta_key = false ) {

	global $wpdb;



	// Make sure everything is valid.

	if ( ! $meta_type )

		return false;



	if ( ! $meta_id = absint( $meta_id ) )

		return false;



	if ( ! $table = _get_meta_table( $meta_type ) )

		return false;



	$column = esc_sql($meta_type . '_id');

	$id_column = 'user' == $meta_type ? 'umeta_id' : 'meta_id';



	// Fetch the meta and go on if it's found.

	if ( $meta = get_metadata_by_mid( $meta_type, $meta_id ) ) {

		$original_key = $meta->meta_key;

		$original_value = $meta->meta_value;

		$object_id = $meta->{$column};



		// If a new meta_key (last parameter) was specified, change the meta key,

		// otherwise use the original key in the update statement.

		if ( false === $meta_key ) {

			$meta_key = $original_key;

		} elseif ( ! is_string( $meta_key ) ) {

			return false;

		}



		// Sanitize the meta

		$_meta_value = $meta_value;

		$meta_value = sanitize_meta( $meta_key, $meta_value, $meta_type );

		$meta_value = maybe_serialize( $meta_value );



		// Format the data query arguments.

		$data = array(

			'meta_key' => $meta_key,

			'meta_value' => $meta_value

		);



		// Format the where query arguments.

		$where = array();

		$where[$id_column] = $meta_id;



		do_action( "update_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );



		if ( 'post' == $meta_type )

			do_action( 'update_postmeta', $meta_id, $object_id, $meta_key, $meta_value );



		// Run the update query, all fields in $data are %s, $where is a %d.

		$result = (bool) $wpdb->update( $table, $data, $where, '%s', '%d' );



		// Clear the caches.

		wp_cache_delete($object_id, $meta_type . '_meta');



		do_action( "updated_{$meta_type}_meta", $meta_id, $object_id, $meta_key, $_meta_value );