RTDB- How to cleanup .off() of listener .on complex ( listener .on in listener .on('child_add...) )

Question

使用Firebase实时数据库，有没有办法清理嵌套在侦听器.on()中的侦听器.on()？

useEffect(() => {

    const ChannelRef = database().ref(`/user/${uid}/channel`);
    ChannelRef.keepSynced(true);
    ChannelRef.on('child_added', channel_id => {
          var startTime = ....
          const threadRef = database().ref(`/channel/${channel_id.key}/Thread`).orderByKey().startAt(startTime);
          threadRef.keepSynced(true);
          threadRef.on('value', thread => {.     <--------------------------------   How to cleanup this listenner ?
            dispatch({
               type: 'AddThread',
               payload: thread.val()
            });
    })


    return () => {
          // CleanUp listenner
           ChannelRef.off();
           ChannelRef.keepSynced(false); 
         
          **// How to cleanup database().ref(`/channel/${channel_id.key}/Thread`).orderByKey().startAt(startTime) ?**
   }
  
}, []

Answer 1

管理这样的监听器并没有什么特别之处。您需要保留所附加的侦听器的列表，然后在效果过期时对它们调用off。