Inserting post_id into guid before wp_insert_post

Question

I would like to insert data into the wp_posts table with the inserted post_id in the 'guid' for a record that doesn't already exist. Below is the closest I've gotten but this doesn't work ($postarr['ID'] is equal to 0).

function filter_handler( $data , $postarr )
{
if($data['post_type']=='ai1ec_event'){
    $my_post_id = $postarr['ID'];
    $data['guid'] = get_option('siteurl') .'/?post_type=ai1ec_event&p='.$my_post_id.'&instance_id=';
}

return $data;
}

add_filter( 'wp_insert_post_data' , 'filter_handler' , '99', 2 );

$mypost = array(
  'post_author'     => 1,
 'post_content'     => 'Test', 
 'post_status'      => 'publish',
 'post_title'       => $_GET['assignment_name'],
 'post_type'        => 'ai1ec_event',
 'guid'     => ''
); 

$postid = wp_insert_post($mypost);

Answer 1

Why would you need that? ID in a database is auto increment - it manages it's value itself. If your target is to set custom guid, you should update the inserted post as soon as it is created via wp_update_post right after your $post_id = wp_inserted_post($mypost); like this:

...Your code above...
$postid = wp_insert_post($mypost);
$data = array(
   'ID' => $postid,
   'guid' => get_option('siteurl') .'/?post_type=ai1ec_event&p='.$postid.'&instance_id='
);
wp_update_post( $data );