How can I display a link to a post's (Word doc or pdf) attachment?

Question

I'm using the code below to first grab the post's attachments (if they're either a Word doc or pdf file), then echoing the url of said attachment. This works great on the first post on a page. However, on each subsequent post the same attachment url is echoed, even if that post doesn't have an attachment. How can I keep that from happening?

$args = array(
                'post_type' => 'attachment',
                'post_mime_type' => array('application/doc','application/pdf'),
                'numberposts' => 1,
                'post_status' => null,
                'post_parent' => $post->ID
            );
$attachments = get_posts( $args );
foreach ($attachments as $attachment) {
    echo '<a href="' . wp_get_attachment_url( $attachment->ID ) . '">Download Spec  Sheet</a>';
    echo '</div>';
}

Answer 1

Try this:

<?php

if ( $attachments = get_children( array(
        'post_type' => 'attachment',
        'post_mime_type' => array('application/doc','application/pdf'),
        'numberposts' => 1,
        'post_status' => null,
        'post_parent' => $post->ID
)));
foreach ($attachments as $attachment) {
echo '<a href="' . wp_get_attachment_url( $attachment->ID ) . '">Download Spec  Sheet</a>';
echo '</div>';
}

?>