wpdb::placeholder_escape(): string

Generates and returns a placeholder escape string for use in queries returned by ::prepare().


Return

string String to escape placeholders.


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Source

File: wp-includes/wp-db.php. View all references

public function placeholder_escape() {
	static $placeholder;

	if ( ! $placeholder ) {
		// If ext/hash is not present, compat.php's hash_hmac() does not support sha256.
		$algo = function_exists( 'hash' ) ? 'sha256' : 'sha1';
		// Old WP installs may not have AUTH_SALT defined.
		$salt = defined( 'AUTH_SALT' ) && AUTH_SALT ? AUTH_SALT : (string) rand();

		$placeholder = '{' . hash_hmac( $algo, uniqid( $salt, true ), $salt ) . '}';
	}

	/*
	 * Add the filter to remove the placeholder escaper. Uses priority 0, so that anything
	 * else attached to this filter will receive the query with the placeholder string removed.
	 */
	if ( false === has_filter( 'query', array( $this, 'remove_placeholder_escape' ) ) ) {
		add_filter( 'query', array( $this, 'remove_placeholder_escape' ), 0 );
	}

	return $placeholder;
}


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Changelog

Changelog
Version Description
4.8.3 Introduced.

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