Attachments Question

[Logikos]

Hey guys, long time no post. Anyway, i have a quick question. I'm trying to make a small mod where members are forced to add attachments when posting a new thread on a specifed forum.

I was going to do:

PHP Code:

if ($foruminfo['isattach'])
{
    $isattach = $DB_site->("
        SELECT attachment
        FROM " . TABLE_PREFIX . "thread
        WHERE threadid = " . $threadinfo['threadid'] . "
        ");

    if ($isattach['attachment'] == 0)    
    {
        // show error
    }
    else
    {
        // let user post
    }
} 


The problem is, the post doesn't make it to the database if there are errors and there is no threadid yet if there are errors. Is there something else i can do, like somewhere that the post is cached or something? Any ideas would be great, thanks.