Prevent publishing the post before setting a featured image?

Question

As the title says , I want a plugin/function to prevent/inform the user when he tries to publish the post without setting the featured image.

ANY HELP ???

Answer 1

<?php
// Something like that should help, but you'll have to play with it to get it working:
// inside your functions.php file
function wpse16372_prevent_publish()
{
    if ( ! is_admin() )
        return;

    // This should be ok, but should be tested:
    $post_id = $GLOBALS['post']->ID;
    echo '<pre>Test for post ID: '; print_r( $post_id ); echo '</pre>';// the actual test

    // has_post_thumbnail() doesn't work/exist on/for admin screens (see your error msg). You need to find another way to test if the post has a thumbnail. Maybe some Javascript?
    //if ( ! has_post_thumbnail( $post_id );
    if ( ! has_post_thumbnail( $post_id ) )
    {
        ?>
        <!-- // 
        <script language="javascript" type="text/javascript">
            alert( 'you have to use a featured image' );
        </script>
        // -->
        <?php
        exit; // abort
    }
}
add_action( 'save_post', 'wpse16372_prevent_publish', 100 );
?>