get_attached_file( $post_id ) wrongly(?) returns the uploads directory when $post_id is not a valid attachment

[mikeschinkel]

The function get_attached_file( $post_id ) wrongly(?) returns the uploads directory when $post_id is not a valid attachment. For example, if I run the following code:

$attached_file = get_attached_file(0);

It might return the following on my machine:

/Users/mikeschinkel/Sites/mysite/public_html/wp-content/uploads/

I would instead expect it to simply return false indicating that no attached file was found:

false

Here is the code I wrote that caused me to recognize the problem:

function has_valid_file_attached( $attachment_id ) {
  return file_exists( get_attached_file( $attachment_id, true ) ) );
}

Here's the hack I had to write instead:

function has_valid_file_attached( $attachment_id ) {
  $attached_file = get_attached_file( $attachment_id, true );
  if ( '/' == substr( $attached_file, -1, 1 ) )
    return false;

  if ( ! file_exists( $attached_file ) )
    return false;

  return true;
}

I have attached a patch that simply returns false when the value returned by the internal call to get_post_meta( $attachment_id, '_wp_attached_file', true ) is an empty string. I would be surprised to find it many people (anyone?) used this function for it's side-effect to return the root upload path so I doubt using this path would break anything.

It's not a critical patch because there is an easy workaround, but it cost me extra time to figure out why my has_valid_file_attached() function wasn't reporting false when the attachment was missing, so it would be nice to keep someone else from having to waste the same time in the future.

Fixes get_attached_file() so that it returns false when the attachment_id is not valid.

This function uses get_post_meta and some images meta data does not include _wp_attached_file , in this case also get_attached_file is returning the incorrect path.

	$file = get_post_meta( $attachment_id, '_wp_attached_file', true );

Why is the get_attached_file using get_post_meta when we have wp_get_attachment_metadata($id) ??

Replying to gandham:

Why is the get_attached_file using get_post_meta when we have wp_get_attachment_metadata($id) ??

wp_get_attachment_metadata() uses get_post_meta() too.

How can we get this moving forward? I've just run into this problem, and was surprised that get_attached_file did not return false.

In [20613]:

Return false in get_attached_file() when the file does not exist, rather than a path to the base uploads directory. props mikeschinkel. fixes #18855.

Still could use unit tests :-)