Example of WP_Error class

wp_Error_example.php

<?php

/**
 * Creating instance of error class
 */
$error = new WP_Error( 'not_found', 'Page Not Found', 'Page Data' );

/**
 * Add new error to object
 */
$error->add( 'not_match', 'Field Not Match' );

/**
 * Return all error codes from object
 *
 * Output: Array ( [0] => not_found [1] => not_match )
 */
$data = $error->get_error_codes();
print_r( $data );

/**
 * Return first error code
 *
 * Output: not_found
 */
echo $error->get_error_code();

/**
 * Return all error message
 *
 * Output: Array ( [0] => Page Not Found [1] => Field Not Match )
 */
$data = $error->get_error_messages();
print_r( $data );

/**
 * Return error message by error code
 *
 * Output: Array ( [0] => Field Not Match )
 */
$data = $error->get_error_messages( 'not_match' );
print_r( $data );

/**
 * Return first error message if no code are given
 *
 * Output: Page Not Found
 */
echo $error->get_error_message();

/**
 * Return first error message for given error code
 *
 * Output: Field Not Match
 */
echo $error->get_error_message( 'not_match' );

/**
 * Return first error data
 *
 * Output: Page Data
 */
echo $error->get_error_data();

/**
 * Return error data from error code.
 *
 * Output: Page Data
 */
echo $error->get_error_data( 'not_found' );

/**
 * add error data to error code
 * syntex: add_data( $data, $code );
 *
 *
 * Output: Some data
 */
$error->add_data( 'Some data', 'not_match' );
echo $error->get_error_data( 'not_match' );

/**
 * Check whether variable is a WordPress Error.
 *
 * return bool True, if WP_Error. False, if not WP_Error.
 * Output: bool(true)
 */
$data = is_wp_error( $error );
var_dump( $data );