def purge_publishers():
    """Removes records from publisher table which no longer have corresponding
    folder on the file system.  If the folder does not exist, we assume that
    the publisher has been deleted.  In any case, one cannot execute the
    publisher if the publisher's folder has been removed.
    """
    pubs = models.Publisher.objects.all()
    # for each record, test for corresponding folder
    for pub in pubs:
        # if folder does not exist
        if not os.path.isdir(pub.path):
            # remove this record
            pub.delete()
            logger.info(
                "Deleting publisher %s which no longer exists at %s"
                % (pub.name, pub.path)
            )