WP_Query::parse_orderby( string $orderby ): string|false

1659	protected function parse_orderby( $orderby ) {1660		global $wpdb;1661 1662		// Used to filter values.1663		$allowed_keys = array(1664			'post_name',1665			'post_author',1666			'post_date',1667			'post_title',1668			'post_modified',1669			'post_parent',1670			'post_type',1671			'name',1672			'author',1673			'date',1674			'title',1675			'modified',1676			'parent',1677			'type',1678			'ID',1679			'menu_order',1680			'comment_count',1681			'rand',1682			'post__in',1683			'post_parent__in',1684			'post_name__in',1685		);1686 1687		$primary_meta_key   = '';1688		$primary_meta_query = false;1689		$meta_clauses       = $this->meta_query->get_clauses();1690		if ( ! empty( $meta_clauses ) ) {1691			$primary_meta_query = reset( $meta_clauses );1692 1693			if ( ! empty( $primary_meta_query['key'] ) ) {1694				$primary_meta_key = $primary_meta_query['key'];1695				$allowed_keys[]   = $primary_meta_key;1696			}1697 1698			$allowed_keys[] = 'meta_value';1699			$allowed_keys[] = 'meta_value_num';1700			$allowed_keys   = array_merge( $allowed_keys, array_keys( $meta_clauses ) );1701		}1702 1703		// If RAND() contains a seed value, sanitize and add to allowed keys.1704		$rand_with_seed = false;1705		if ( preg_match( '/RAND\(([0-9]+)\)/i', $orderby, $matches ) ) {1706			$orderby        = sprintf( 'RAND(%s)', (int) $matches[1] );1707			$allowed_keys[] = $orderby;1708			$rand_with_seed = true;1709		}1710 1711		if ( ! in_array( $orderby, $allowed_keys, true ) ) {1712			return false;1713		}1714 1715		$orderby_clause = '';1716 1717		switch ( $orderby ) {1718			case 'post_name':1719			case 'post_author':1720			case 'post_date':1721			case 'post_title':1722			case 'post_modified':1723			case 'post_parent':1724			case 'post_type':1725			case 'ID':1726			case 'menu_order':1727			case 'comment_count':1728				$orderby_clause = "{$wpdb->posts}.{$orderby}";1729				break;1730			case 'rand':1731				$orderby_clause = 'RAND()';1732				break;1733			case $primary_meta_key:1734			case 'meta_value':1735				if ( ! empty( $primary_meta_query['type'] ) ) {1736					$orderby_clause = "CAST({$primary_meta_query['alias']}.meta_value AS {$primary_meta_query['cast']})";1737				} else {1738					$orderby_clause = "{$primary_meta_query['alias']}.meta_value";