云开发 如何接收session-from传的参数

<button class="btn_like btn_join" open-type="contact" show-message-card="true" send-message-title="加入粉丝群" session-from="{{mediaId}}" send-message-img="/images/default_img.png" send-message-path="/pages/lordHome/lordHome"
        bindcontact="handleContact">
      <text>加入社群</text>
    </button>