def entry_not_deleted
    if DeletedEntry.where('feed_id = ? AND (guid = ? OR unique_hash = ?)', self.feed_id, self.guid, self.unique_hash).exists?
      Rails.logger.debug "Entry not valid: already deleted entry - guid: #{self.try :guid}, unique_hash: #{self.try :unique_hash}, published: #{self.try :published}, feed_id: #{self.feed_id}, feed title: #{self.feed.title}"
      errors.add :base, 'entry already deleted'