Question

我正在尝试在触发侦听器时获取路径或父级例如。

// Setting Listener on friends info CHANGE

  database.reference().child('user/$k/info').onChildChanged.listen((event){
    print('Triggered Listener on -- CHANGED -- friend info');

    // I want to get the variable k here or the parent value of info when the 
        // listener is triggered

  }),

Answer 1

我的同事帮助我更好地了解了闭包。因为我在forEach中调用了listen函数，所以当侦听器触发时，我可以访问$ k变量。

    var values = new Map<String, dynamic>.from(snapshot.value);
    values.forEach((k, v) =>
    {
      // k represents each friend's uid pulled from the user's friend list
      // Settings Listener on friends info CHANGE
      database.reference().child('user/$k/info').onChildChanged.listen((event){
        print('$k'); // <- The user ID I was looking for
        print('Triggered Listener on -- CHANGED -- friend info');
        print('info that changed: ${event.snapshot.key}: ${event.snapshot.value}');
      }),```

Firebase波动Firebase数据库事件上的Firebase路径或父级（onValue，onChildChanged）

1 个答案: