Mass/Bulk assign featured images to posts

Question

I have a text file with post ids and attachment ids like so:

post_id,attachment_id
post_id,attachment_id
post_id,attachment_id
post_id,attachment_id

I then try to use a function inside my functions.php file like so:

function addimg() {
$fh = @fopen( dirname( __FILE__ ) . '/addimg.txt', 'r' );

if ( $fh ) {
    while ( ( $line = fgets( $fh ) ) !== false ) {
        $ids = explode( ',', $line );
        array_walk( $ids, 'trim' );
        $postid = array_shift( $ids );
        set_post_thumbnail( $postid, $ids );
    }
}
}
add_action('wp_head', 'addimg');

But nothing happens.

I've used the same procedure to add categories to posts and it works. I've also tried to manually add a featured image to a post like so:

function thumb() {

set_post_thumbnail( 1, 1);

}
add_action('wp_head', 'thumb');

And that works.

So my knowledge is too shallow to understand why what I'm trying to do doesn't work?

Answer 1

As you don't have much programming experience, I'll post a ready-to-use solution here. I've looked at your code a little longer, and the problem is that after array_shift, $ids is still an array. set_post_thumbnail expects and integer, not an array. You could use $ids[0] as the second parameter, but the following is a cleaner solution, in my opinion.

function wpse149149_addimg() {
    $fh = @fopen( dirname( __FILE__ ) . '/addimg.txt', 'r' );

    if ( $fh ) {
        while ( ( $line = fgets( $fh ) ) !== false ) {
            $ids = explode( ',', $line );
            array_walk( $ids, 'trim' );
            set_post_thumbnail( $ids[0], $ids[1] );
        }
    }
}

add_action( 'wp_head', 'wpse149149_addimg' );