dwp-guten/metabox.php

<?php

function dw_guten_register_media_meta() {
	register_meta('post', 'media', array(
		'show_in_rest' => true,
		'type' => 'string',
		'single' => true,
		'sanitize_callback' => 'sanitize_text_field',
		'auth_callback' => function() { 
			return current_user_can('edit_posts');
		}
	));
}
add_action('init', 'dw_guten_register_media_meta');

function dw_guten_register_desc_meta() {
	register_meta('post', 'meta_desc', array(
		'show_in_rest' => true,
		'type' => 'string',
		'single' => true,
		'sanitize_callback' => 'sanitize_text_field',
		'auth_callback' => function() { 
			return current_user_can('edit_posts');
		}
	));
}
add_action('init', 'dw_guten_register_desc_meta');

function dw_guten_add_media_meta_box() {
	add_meta_box( 
		'dw_guten_post_options_metabox', 
		'Post Options', 
		'dw_guten_post_options_metabox_html', 
		'post', 
		'normal', 
		'default',
		array('__back_compat_meta_box' => true)
	);
}
add_action( 'add_meta_boxes', 'dw_guten_add_media_meta_box' );

function dw_guten_add_desc_meta_box() {
	add_meta_box( 
		'dw_guten_post_options_metabox', 
		'Post Options', 
		'dw_guten_post_options_metabox_desc', 
		'post', 
		'normal', 
		'default',
		array('__back_compat_meta_box' => true)
	);
}
add_action( 'add_meta_boxes', 'dw_guten_add_desc_meta_box' );

function dw_guten_post_options_metabox_html($post) {
    $field_value = get_post_meta($post->ID, 'media', true);
    wp_nonce_field( 'dw_guten_update_post_metabox', 'dw_guten_update_post_nonce' );
    ?>
    <p>
        <label for="dw_guten_media_metafield"><?php esc_html_e( 'Media URL', 'textdomain' ); ?></label>
        <br />
        <input class="widefat" type="text" name="dw_guten_media_metafield" id="dw_guten_media_metafield" value="<?php echo esc_attr( $field_value ); ?>" />
    </p>
    <?php
}

function dw_guten_post_options_metabox_desc($post) {
    $field_value = get_post_meta($post->ID, 'media', true);
    wp_nonce_field( 'dw_guten_update_post_metabox_desc', 'dw_guten_update_post_nonce' );
    ?>
    <p>
        <label for="dw_guten_desc_metafield"><?php esc_html_e( 'Meta Excerpt', 'textdomain' ); ?></label>
        <br />
        <input class="widefat" type="text" name="dw_guten_desc_metafield" id="dw_guten_desc_metafield" value="<?php echo esc_attr( $field_value ); ?>" />
    </p>
    <?php
}

function dw_guten_save_post_metabox($post_id, $post) {
    $edit_cap = get_post_type_object( $post->post_type )->cap->edit_post;
    if( !current_user_can( $edit_cap, $post_id )) {
        return;
    }
    if( !isset( $_POST['dw_guten_update_post_nonce']) || !wp_verify_nonce( $_POST['dw_guten_update_post_nonce'], 'dw_guten_update_post_metabox' )) {
        return;
    }

    if(array_key_exists('dw_guten_media_metafield', $_POST)) {
        update_post_meta( 
            $post_id, 
            'media', 
            sanitize_text_field($_POST['dw_guten_media_metafield'])
        );
    }
}
add_action( 'save_post', 'dw_guten_save_post_metabox', 10, 2 );

function dw_guten_save_post_metabox_desc($post_id, $post) {
    $edit_cap = get_post_type_object( $post->post_type )->cap->edit_post;
    if( !current_user_can( $edit_cap, $post_id )) {
        return;
    }
    if( !isset( $_POST['dw_guten_update_post_nonce_desc']) || !wp_verify_nonce( $_POST['dw_guten_update_post_nonce_desc'], 'dw_guten_update_post_metabox_desc' )) {
        return;
    }

    if(array_key_exists('dw_guten_desc_metafield', $_POST)) {
        update_post_meta( 
            $post_id, 
            'meta_desc', 
            sanitize_text_field($_POST['dw_guten_desc_metafield'])
        );
    }
}
add_action( 'save_post', 'dw_guten_save_post_metabox_desc', 10, 2 );