code: def get_redirect_url(self, url, encrypt_code, card_id):
          
          from wechatpy.utils import WeChatSigner
  
          code = self.decrypt_code(encrypt_code)
  
          signer = WeChatSigner()
          signer.add_data(self.secret)
          signer.add_data(code)
          signer.add_data(card_id)
          signature = signer.signature
  
          r = '{url}?encrypt_code={code}&card_id={card_id}&signature={signature}'
          return r.format(
              url=url,
              code=encrypt_code,
              card_id=card_id,
              signature=signature
          )
docs: 获取卡券跳转外链