Visibility Check Box mit Beitrag

class Sgr_Visibility_Meta_Box {

	public function __construct() {

		if ( is_admin() ) {
			add_action( 'load-post.php',     array( $this, 'init_metabox' ) );
			add_action( 'load-post-new.php', array( $this, 'init_metabox' ) );
		}

	}

	public function init_metabox() {

		add_action( 'add_meta_boxes',        array( $this, 'add_metabox' )         );
		add_action( 'save_post',             array( $this, 'save_metabox' ), 10, 2 );

	}

	public function add_metabox() {

		add_meta_box(
			'sgr_visibility_meta',
			__( 'Platzierung des Beitrags', 'sgr' ),
			array( $this, 'sgr_render_visibility_metabox' ),
			'post',
			'side',
			'high'
		);

	}

	public function sgr_render_visibility_metabox( $post ) {

		// Add nonce for security and authentication.
		wp_nonce_field( 'sgr_nonce_action', 'sgr_nonce' );

		// Retrieve an existing value from the database.
		$sgr_homepage = get_post_meta( $post->ID, 'sgr_homepage', true );
		$sgr_fb_page = get_post_meta( $post->ID, 'sgr_fb_page', true );
		$sgr_article_event_date = get_post_meta( $post->ID, 'sgr_article_event_date', true );

		// Set default values.
		if( empty( $sgr_article_event_date ) ) $sgr_article_event_date = '';

		// Form fields.
		echo '<table class="form-table">';

		echo '	<tr>';
		echo '		<th><label for="sgr_visibility_checkbox" class="sgr_visibility_checkbox_label">' . __( 'Der Beitrag erscheint zusätzlich auf folgenden Seiten:', 'sgr' ) . '</label></th>';
		echo '		<td>';
		echo '			<label><input type="checkbox" name="sgr_homepage" class="sgr_visibility_checkbox_field" value="' . $sgr_homepage . '" ' . checked( $sgr_homepage, 'checked', false ) . '> ' . __( 'Startseite', 'sgr' ) . '</label><br>';
		echo '			<label><input type="checkbox" name="sgr_fb_page" class="sgr_visibility_checkbox_field" value="' . $sgr_fb_page . '" ' . checked( $sgr_fb_page, 'checked', false ) . '> ' . __( 'Fachbereichsseite', 'sgr' ) . '</label><br>';
		echo '		</td>';
		echo '	</tr>';

		echo '	<tr>';
		echo '		<th><label for="sgr_article_event_date" class="sgr_article_event_date_label">' . __( 'Veranstaltungsdatum (dd.mm.yyyy)', 'sgr' ) . '</label></th>';
		echo '		<td>';
		echo '			<input type="text" id="sgr_article_event_date" name="sgr_article_event_date" class="sgr_article_event_date_field" placeholder="' . esc_attr__( '', 'sgr' ) . '" value="' . esc_attr( $sgr_article_event_date ) . '">';
		echo '			<p class="description">' . __( 'Tragen Sie hier das Datum der Veranstaltung ein, auf die sich der Beitrag bezieht.', 'sgr' ) . '</p>';
		echo '		</td>';
		echo '	</tr>';

		echo '</table>';

	}

	public function save_metabox( $post_id, $post ) {

		// Add nonce for security and authentication.
		$nonce_name   = isset( $_POST['sgr_nonce'] ) ? $_POST['sgr_nonce'] : '';
		$nonce_action = 'sgr_nonce_action';

		// Check if a nonce is set.
		if ( ! isset( $nonce_name ) )
			return;

		// Check if a nonce is valid.
		if ( ! wp_verify_nonce( $nonce_name, $nonce_action ) )
			return;

		// Check if the user has permissions to save data.
		if ( ! current_user_can( 'edit_post', $post_id ) )
			return;

		// Check if it's not an autosave.
		if ( wp_is_post_autosave( $post_id ) )
			return;

		// Check if it's not a revision.
		if ( wp_is_post_revision( $post_id ) )
			return;

		// Sanitize user input.
		$sgr_new_homepage = isset( $_POST[ 'sgr_homepage' ] ) ? 'checked' : '';
		$sgr_new_fb_page = isset( $_POST[ 'sgr_fb_page' ] ) ? 'checked' : '';
		$sgr_new_article_event_date = isset( $_POST[ 'sgr_article_event_date' ] ) ? sanitize_text_field( $_POST[ 'sgr_article_event_date' ] ) : '';

		// Update the meta field in the database.
		update_post_meta( $post_id, 'sgr_homepage', $sgr_new_homepage );
		update_post_meta( $post_id, 'sgr_fb_page', $sgr_new_fb_page );
		update_post_meta( $post_id, 'sgr_article_event_date', $sgr_new_article_event_date );

	}

}

new Sgr_Visibility_Meta_Box;