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has_post_thumbnail seems to be working fine but the_post_thumbnail returns nothing.

here is my code:

if ($favorite_post_ids):
    foreach ($favorite_post_ids as $post_id) {
            $p = get_post($post_id);
            echo "<li>";
            echo "<a href='".get_permalink($post_id)."' title='". $p->post_title ."'>" . $p->post_title . "</a> ";
            if (has_post_thumbnail($post_id))
                echo $post_id;
            echo "</li>";

Here is the sample output:

* Post101 remove 101
* Post97 remove 97
* Post59 remove 59

Most of the code above is irrelevant, I just included it for clarity. I have echoed the $post_id to make sure that it is passing the if (has_post_thumbnail($post_id)), which it does but the_post_thumbnail fails silently. I tried echoing it too but that returns nothing either.

I have got post_thumbnails turned on in the theme:

if ( function_exists( 'add_theme_support' ) ) { 
  add_theme_support( 'post-thumbnails' ); 

any ideas? thanks

share|improve this question
up vote 4 down vote accepted

You're passing an invalid argument to the_post_thumbnail().

Here's your code: the_post_thumbnail($post_id);

Here's what the_post_thumbnail() expects: the_post_thumbnail( $size, $attr );

The function is expecting a $size as the first argument. Since $post_id is not a valid $size, the function doesn't know what to output.

share|improve this answer
You could try echo get_the_post_thumbnail( $id, $size, $attr ); codex.wordpress.org/Function_Reference/get_the_post_thumbnail – goldenapples Apr 15 '11 at 1:08
thanks guys. shoulda looked up the code ref! used this: echo get_the_post_thumbnail( $post_id, 'thumbnail' ); – edzillion Apr 15 '11 at 13:59

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