如何在客户端失去连接时从 Firebase 实时数据库中删除数据

Question

我正在开发一款游戏，将两个玩家与Firebase实时数据连接起来。 但我想要一种方法，如果失去与互联网的连接，可以删除玩家数据。

Answer 1

这可以通过 OnDisconnect 方法进行更新。

弗兰克的这个原始答案最初描述了有关OnT断开连接方法的更多详细信息。

在此处阅读有关界面的更多信息。

您可以使用此 Firebase 示例设置"已连接状态"，该示例使用实时数据库和云功能以及 OnDisconnect 来显示用户的状态。从示例中提取：

var userStatusDatabaseRef = firebase.database().ref('/status/' + uid);
firebase.database().ref('.info/connected').on('value', function(snapshot) {
    // If we're not currently connected, don't do anything.
    if (snapshot.val() == false) {
        return;
    };
    // If we are currently connected, then use the 'onDisconnect()'
    // method to add a set which will only trigger once this
    // client has disconnected by closing the app,
    // losing internet, or any other means.
    userStatusDatabaseRef.onDisconnect().set(isOfflineForDatabase).then(function() {
        // The promise returned from .onDisconnect().set() will
        // resolve as soon as the server acknowledges the onDisconnect()
        // request, NOT once we've actually disconnected:
        // https://firebase.google.com/docs/reference/js/firebase.database.OnDisconnect
        // We can now safely set ourselves as 'online' knowing that the
        // server will mark us as offline once we lose connection.
        userStatusDatabaseRef.set(isOnlineForDatabase);
    });
});