客户地址字段为空时如何禁止打印发票

这是打印的功能。我试过这个代码,但什么都没有发生

      def invoice_print(self,cr,uid,values):
    """ Print the invoice and mark it as sent, so that we can see more
        easily the next step of the workflow
    """
    res_partner = self.pool.get('res.partner')
    adresse_partner = res_partner.browse(cr, uid, values.get('partner_id')).street
    code_tva_partner = res_partner.browse(cr, uid, values.get('partner_id')).CodeTVA
    if (code_tva_partner==False)or (adresse_partner==False) :
        raise UserError(_(
            "you cannot print invoice unless you enter partner adress and code TVA "))
    elif (code_tva_partner==True) and (adresse_partner==True):
      self.ensure_one()
      self.sent = True
    return self.env['report'].get_action(self, 'account.report_invoice')