/**
* Require a featured image to be set before a post can be published.
*/
add_filter( 'wp_insert_post_data', function ( $data, $postarr ) {
$post_id = $postarr['ID'];
$post_status = $data['post_status'];
$original_post_status = $postarr['original_post_status'];
if ( $post_id && 'publish' === $post_status && 'publish' !== $original_post_status ) {
$post_type = get_post_type( $post_id );
if ( post_type_supports( $post_type, 'thumbnail' ) && ! has_post_thumbnail( $post_id ) ) {
$data['post_status'] = 'draft';
}
}
return $data;
}, 10, 2 );
add_action( 'admin_notices', function () {
$post = get_post();
if ( 'publish' !== get_post_status( $post->ID ) && ! has_post_thumbnail( $post->ID ) && !empty($post->post_title) ) {
?>
}
} );