Check post on publish for blank title

Question

I have several wp users who do not insert a title when creating a new post (and custom type post). This means that the permalink is assigned a number as the link. Within the multisite I am developing, this will commonly stop the link from working (the page just refreshes).

I want to show a warning message when the user fails to insert a title on the post before publishing (telling them to insert title AND edit the permalink).

My code so far in the functions.php file:

function check_for_post_title( $post, $ID )
{
    $title = $post->post_title;
    $permalink = get_permalink( $ID );
    if($title =='' || $title == null) {
        no_post_title_notice();
    } else {
        some_post_title_notice();
    }
}
add_action( 'publish_post', 'check_for_post_title', 10, 2 );

function no_post_title_notice() {
    ?>
    <div class="notice notice-warning is-dismissible">
        <p><?php _e( 'You have not provided a title for your post/page. This will cause the link to be broken. Please revise', 'understrap-post-title' ); ?></p>
    </div>
    <?php
}

function some_post_title_notice() {
    ?>
    <div class="notice notice-warning is-dismissible">
        <p><?php _e( 'I dont know why this message is appearing', 'understrap-post-title' ); ?></p>
    </div>
    <?php
}

Currently, it's not working and no notices are appearing at the top of the edit post screen after publishing/updating at all. Not sure why it is not firing at all (even the 'else' statement should fire something). What am I doing wrong?

Answer 1

Your error doesn't appears on the screen because the page is reloaded after the action publish_post.

I have followed a different approach altogether, I'm checking the post title at wp_insert_post_data if the title is empty, I mark the post_status as draft and save a simple flag in options table. The flag I've saved is used to hide the Post Published notice and display a admin notice for specifying title in order to publish the post.

At the same moment I delete the option, so the notice is one time thing. You can modify it to a greater extent as per your requirements, but this is a basic solution and should work fine.

/**
 * Checks for empty post title, if empty sets the post status to draft
 *
 * @param $data
 * @param $postarr
 *
 * @return array
 */
function wse_279994_check_post_title( $data, $postarr ) {
    if ( is_array( $data ) && 'publish' == $data['post_status'] && empty( $data['post_title'] ) ) {
        $data['post_status'] = 'draft';
        update_option( 'wse_279994_post_error', 'empty_title' );
    }

    return $data;
}
add_filter( 'wp_insert_post_data', 'wse_279994_check_post_title', 10, 2 );

/**
 * If the post title was empty, do not show post published message
 */
add_filter( 'post_updated_messages', 'wse_279994_remove_all_messages' );

function wse_279994_remove_all_messages( $messages ) {
    if ( get_option( 'wse_279994_post_error' ) ) {
        return array();
    } else {
        return $messages;
    }
}

/**
 * Show admin notice for empty post title
 */
add_action( 'admin_notices', 'wse_279994_show_error' );
function wse_279994_show_error() {
    $screen = get_current_screen();
    if ( $screen->id != 'post' ) {
        return;
    }
    if ( ! get_option( 'wse_279994_post_error' ) ) {
        return;
    }
    echo '<div class="error"><p>' . esc_html__( "You need to enter a Post Title in order to publish it.", "wse" ) . '</p></div>';
    delete_option( 'wse_279994_post_error' );
}

Answer 2

For Custom post type Demo modified above answer

/**
 * Checks for empty post title, if empty sets the post status to draft
 *
 * @param $data
 * @param $postarr
 *
 * @return array
 */
function wse_279994_check_post_title( $data, $postarr ) {
    global $post;
    if( "demo" == get_post_type($post) ){
       if ( is_array( $data ) && 'publish' == $data['post_status'] && empty( $data['post_title'] ) ) {
         $data['post_status'] = 'draft';
         update_option( 'wse_279994_post_error', 'empty_title' );
     }
   }

    return $data;
}
add_filter( 'wp_insert_post_data', 'wse_279994_check_post_title', 10, 2 );