Question

我正在使用Transaction来通过Unity3D和RealTime数据库保存排行榜得分。我的最终目标是：

查找UserID是否已存在于数据库排行榜中。
如果存在UserID，则检查（来自游戏）的新分数是否更高比旧分数（来自数据库）要大的话，如果删除，请删除旧分数并放置新分数。
如果UserID不存在，则添加新分数（如果更高）比整个数据库列表中最低的分数高。 现在从下面的代码示例中所做的几乎是什么。

我想到的一种方法是按score对列表进行排序，然后我就可以逐个传递整个列表并找到userID的位置和得分，然后以某种方式删除找到的userID并放置新的得分。

我试图对其进行排序，但是似乎没有任何东西可以在这里进行排序。

毫无疑问，这是一个棘手的问题。

代码：

TransactionResult AddScoreTransaction(MutableData mutableData) {
    List<object> leaders = mutableData.Value as List<object>;

    if (leaders == null) {
        leaders = new List<object>();
    } else if (mutableData.ChildrenCount >= MaxScores) {
        // If the current list of scores is greater or equal to our maximum allowed number,
        // we see if the new score should be added and remove the lowest existing score.
        long minScore = long.MaxValue;
        object minVal = null;
        foreach (var child in leaders) {
            if (!(child is Dictionary<string, object>))
                continue;
            long childScore = (long)((Dictionary<string, object>)child)["score"];
            if (childScore < minScore) {
                minScore = childScore;
                minVal = child;
            }
        }
        // If the new score is lower than the current minimum, we abort.
        if (minScore > score) {
            return TransactionResult.Abort();
        }
        // Otherwise, we remove the current lowest to be replaced with the new score.
        leaders.Remove(minVal);
    }

    // Now we add the new score as a new entry that contains the email address and score.
    Dictionary<string, object> newScoreMap = new Dictionary<string, object>();
    newScoreMap["score"] = score;
    newScoreMap["email"] = email;
    newScoreMap["userId"] = userId;
    leaders.Add(newScoreMap);

    // You must set the Value to indicate data at that location has changed.
    mutableData.Value = leaders;
    return TransactionResult.Success(mutableData);
}

public void AddScore() {
    if (score == 0 || string.IsNullOrEmpty(email)) {
        DebugLog("invalid score or email.");
        return;
    }
    DebugLog(String.Format("Attempting to add score {0} {1}", email, score.ToString()));

    DatabaseReference reference = FirebaseDatabase.DefaultInstance.GetReference("Leaders").Child("ClassA");

    DebugLog("Running Transaction...");
    // Use a transaction to ensure that we do not encounter issues with
    // simultaneous updates that otherwise might create more than MaxScores top scores.
    reference.RunTransaction(AddScoreTransaction)
        .ContinueWith(task => {
        if (task.Exception != null) {
            DebugLog(task.Exception.ToString());
        } else if (task.IsCompleted) {
            DebugLog("Transaction complete.");
        }
    });
}

如何使用Firebase实时数据库通过排行榜更新UserID，

0 个答案: