How can I run this code once so that my generated post title doesn't keep changing on publish/update?

Question

I have a custom post type called transaction, and on the post type's edit/publish screen I have removed the post title field. The post title is now being generated by the function below, which labels each post Transaction followed by a unique string, thanks to the uniqid PHP function.

I'm running this function on the title_save_pre filter but every time I update the post, a new unique number being generated for the title.

How can I modify the code below so that the unique number for the title is only generated once?

function transaction_title( $title ) {

  $screen = get_current_screen();
  $transaction_number = uniqid(); // unique number

  if ( 'transaction' == $screen->post_type ) {
     return 'Transaction '. $transaction_number;
  } else {
    return $title; // else return the normal title
  }
}
add_filter( 'title_save_pre', 'transaction_title');

My initial thoughts are to set a post meta flag like this but I'm having trouble combining it with my function. It seems that it only updates the post meta when I use the transition_post_status action and doesn't with my title_save_pre filter (which I need to change the title).

Answer 1

function transaction_title( $title )
{


    if ( 'transaction' == get_current_screen()->post_type && '' == $title )
    {
        return 'Transaction '.uniqid();
    }
    // else return the normal title
    else 
    {
        return $title;
    }
}
add_filter( 'title_save_pre', 'transaction_title' );

Answer 2

Have you tried using wp_insert_post_data() ? This question may also help you.