[WordPress] Displaying Custom Messages in WordPress, Part 2

00-markup-for-the-settings-page.html

<div class="wrap">

	<h1>Acme Options Pages</h1>
	<?php do_action( 'get_acme_settings_messages' ); ?>
	
	<form method="post" action="<?php echo esc_html( admin_url( 'admin-post.php' ) ); ?>">

    		<!-- TODO: This is where we render the rest of the page. -->

		<?php
			wp_nonce_field( 'yhd-settings-save', 'yellow-house-design-directory-importer' );
			submit_button();
		?>

	</form>

</div><!-- .wrap -->

01-wiring-up-the-custom-action.php

<?php

public function init() {

	add_action(
		'get_acme_settings_messages',
		array( $this, 'get_messages' )
	);

}

02-get-messages.php

<?php

public function get_messages() {

	$this->get_errors();
	$this->display_errors();

}

03-get-errors.php

<?php

private function get_errors() {

	$this->errors = get_option( 'acme-errors' );
	delete_option( 'acme-errors' );

}

04-display-errors.php

<?php

private function display_errors() {

	if ( empty( $this->errors ) ) {
		return;
	}

	// Create the list of errors.
	$errors = '<ul>';
	foreach ( $this->errors as $error ) {
		$errors .= '<li>' . $error . '</li>';
	}
	$errors .= '</ul>';

	// Create the markup for the error message.
	$html = "
		<div class='notice notice-error'>
			$errors
		</div><!-- .notice-error -->
	";

	// Set the HTML we'll allow for sanitization.
	$allowed_html = array(
		'div' => array(
			'class' => array(),
		),
		'ul' => array(),
		'li' => array(),
	);

	echo wp_kses( $html, $allowed_html );

}