WP - change upload dir based on post_type

gistfile1.php

// Save uploads for Products to a products subdir & Artists to an Artist dir
function reroute_upload_dir ( $pathdata ) {

  $post_type = ( isset( $_POST['post_id'] ) ) ? get_post_type( $_POST['post_id'] ) : false;

  if ( $post_type == 'product' ) {
    $subdir = '/products';
  } elseif ( $post_type == 'artists' ) {
    $subdir = '/artists';
  } elseif ( $post_type === 'post' ) {
    $subdir = '/blog';
  } else {
    $subdir = '';
  }

  if ( empty( $pathdata['subdir'] ) ) {
    $pathdata['path']   = $pathdata['path'] . $subdir;
    $pathdata['url']    = $pathdata['url']. $subdir;
    $pathdata['subdir'] = $subdir;
  } else {
    $new_subdir = $subdir . $pathdata['subdir'];

    $pathdata['path']   = str_replace( $pathdata['subdir'], $new_subdir, $pathdata['path'] );
    $pathdata['url']    = str_replace( $pathdata['subdir'], $new_subdir, $pathdata['url'] );
    $pathdata['subdir'] = str_replace( $pathdata['subdir'], $new_subdir, $pathdata['subdir'] );
  }

  return $pathdata;
}
add_filter( 'upload_dir', 'reroute_upload_dir' );