Adding Metaboxes to Genesis CPT Archive Settings, walkthrough publishing August 7th at https://joshuadnelson.com/blog

add-metabox-to-genesis-cpt-archive-settings.php

<?php
/**
 * Add custom metabox to Genesis CPT Archive Settings.
 *
 * @author Joshua David Nelson, josh@joshuadnelson.com
 * 
 * @link https://joshuadnelson.com/adding-metaboxes-to-genesis-cpt-archive-settings
 */
class JDN_Genesis_CPT_Archive_Settings {
	
	/**
	 * Build the class
	 */
	public function __construct() {
		// Init
		add_action( 'init', array( $this, 'init' ) );
	}
	
	/**
	 * Hooks and such
	 */
	public function init() {

		// Register the metabox
		add_action( 'genesis_cpt_archives_settings_metaboxes', array( $this, 'register_cpt_metaboxes' ) );
		
		// Sanitize the submitted values
		add_action( 'genesis_settings_sanitizer_init', array( $this, 'sanitization' ) );

		// Set default values
		add_action( 'genesis_cpt_archive_settings_defaults', array( $this, 'cpt_archive_setting_defaults' ) );
		
	}
		
	/**
	 * Set the default.
	 *
	 * @param string $defaults 
	 * @return string $defaults
	 */
	function cpt_archive_setting_defaults( $defaults ) {
		
		// Default Subtitle Value
		$defaults[ 'subtitle' ] = 'default subtitle';
		
		return $defaults;
	}

	/**
	 * Register the metabox.
	 *
	 * @param string $_genesis_cpt_archives_settings_pagehook
	 */
	function register_cpt_metaboxes( $_genesis_cpt_archives_settings_pagehook ) {
		
		// Add meta box
		add_meta_box( 'page_options', __( 'Archive Template Options', 'domain' ), array( $this, 'custom_archive_options' ), $_genesis_cpt_archives_settings_pagehook, 'main', 'high');
		
	}

	/**
	 * Custom archive options.
	 */
	function custom_archive_options() {
		
		// Get the current post type from the $_GET
		if( isset( $_GET['post_type'] ) ) {
			$post_type = $_GET['post_type'];
		
		// If there's not a 'post_type' value, see if we can grab it from the settings page slug.
		// I know, this is a little bass-ackwards, but it works.
		} elseif( isset( $_GET['page'] ) ) {
			$post_type = str_replace( "genesis-cpt-archive-", "", $_GET['page'] );
		
		// If all else fails, jump ship.
		} else {
			return;
		}
		
		// Make sure you have a valid post type and it's one of the post types you want this to appear on
		if( is_string( $post_type ) && in_array( $post_type, array( 'project', 'staff' ) ) ) {
			echo '<p><label for="' . GENESIS_CPT_ARCHIVE_SETTINGS_FIELD_PREFIX . esc_attr( $post_type ) . '[subtitle]"><b>Subtitle</b></label></p>';
			echo '<p><input type="text"  name="' . GENESIS_CPT_ARCHIVE_SETTINGS_FIELD_PREFIX . esc_attr( $post_type ) . '[subtitle]" value="' . genesis_get_option( 'subtitle', GENESIS_CPT_ARCHIVE_SETTINGS_FIELD_PREFIX . $post_type ) . '"/></p>';
		}
	}

	/** 
	 * Sanitize the submitted vsalues.
	 */
	function sanitization() {
	
		// Add the `no_html` filter to the subtitle field
		genesis_add_option_filter( 'no_html', GENESIS_SETTINGS_FIELD,
		array(
			'subtitle',
		) );
		
	}
} // end class

global $_jdn_genesis_cpt_archive_settings;
$_jdn_genesis_cpt_archive_settings = new JDN_Genesis_CPT_Archive_Settings;

add-post-type-support.php

<?php
/**
 * Add post type support for Genesis Custom Post Type Archive Settings.
 *
 * @author Joshua David Nelson, josh@joshuadnelson.com
 * 
 * @link https://joshuadnelson.com/adding-metaboxes-to-genesis-cpt-archive-settings
 */
// Option 1: When registering the post type, add 'genesis-cpt-archives-settings' in the 'supports' argument
// 	See: http://codex.wordpress.org/Function_Reference/register_post_type
$args = array(
	'post_type' => 'project',
	'supports' => array( 'editor', 'title', 'genesis-cpt-archives-settings' ),
);
register_post_type( 'project', $args );

// Option 2: After a post type is registered, you can add support.
// 	See: https://codex.wordpress.org/Function_Reference/add_post_type_support
add_post_type_support( 'project', 'genesis-cpt-archives-settings' );

archive-staff.php

<?php
/**
 * Template for Staff Archive.
 * 
 * @link https://joshuadnelson.com/adding-metaboxes-to-genesis-cpt-archive-settings
 *
 * @package 	Child_Theme
 * @since       1.0.0
 * @author      Joshua Nelson <josh@joshuadnelson.com>
 * @license     http://opensource.org/licenses/gpl-2.0.php GNU Public License
 */

add_action( 'genesis_meta', 'jdn_staff_archive__hooks' );
/**
 * The page hooks.
 */
function jdn_staff_archive__hooks() {
	
	// Replace Generic title description with custom title, subtitle, & description
	remove_action( 'genesis_before_loop', 'genesis_do_cpt_archive_title_description' );
	add_action( 'genesis_before_loop', 'jdn_staff_archive_title_description' );
	
}

/**
 * Add custom headline and description to relevant custom post type archive pages.
 *
 * @see genesis_do_cpt_archive_title_description
 *
 * @uses genesis_has_post_type_archive_support() Check if a post type should potentially support an archive setting page.
 * @uses genesis_get_cpt_option()                Get list of custom post types which need an archive settings page.
 *
 * @return null Return early if not on relevant post type archive.
 */
function jdn_staff_archive_title_description() {

	if ( ! is_post_type_archive() || ! genesis_has_post_type_archive_support() )
		return;

	$headline = genesis_get_cpt_option( 'headline' );

	if ( empty( $headline ) && genesis_a11y( 'headings' ) ) {
		$headline = post_type_archive_title( '', false );
	}

	$intro_text = genesis_get_cpt_option( 'intro_text' );

	$headline   = $headline ? sprintf( '<h1 %s>%s</h1>', genesis_attr( 'archive-title' ), strip_tags( $headline ) ) : '';
	$intro_text = $intro_text ? apply_filters( 'genesis_cpt_archive_intro_text_output', $intro_text ) : '';
	
	// Only displays subtitle if the main archive headline or intro text are also present
	if ( $headline || $intro_text ) {
		$subtitle = genesis_get_cpt_option( 'subtitle' );
		if( !empty( $subtitle ) )
			$headline .= '<h4 class="subtitle">' . esc_attr( $subtitle ) . '</h4>';
		
		printf( '<div %s>%s</div>', genesis_attr( 'cpt-archive-description' ), $headline . $intro_text );
			
	}
}

genesis();

get-cpt-archive-meta.php

<?php
/**
 * Get the custom meta from the Genesis CPT Archive Settings. Please this in your template.
 *
 * @author Joshua David Nelson, josh@joshuadnelson.com
 * 
 * @link https://joshuadnelson.com/adding-metaboxes-to-genesis-cpt-archive-settings
 */
$subtitle = genesis_get_cpt_option( 'subtitle' );
if( !empty( $subtitle ) )
	echo '<h4 class="subtitle">' . esc_attr( $subtitle ) . '</h4>';