我如何使用响应式扩展来限制searchpane . suggested srequested

Question

响应式扩展允许我"观察"事件流。例如，当用户在Windows 8搜索窗格中输入他们的搜索查询时，建议请求会一遍又一遍地出现(对于每个字母)。我如何利用响应式扩展来限制请求?

像这样:

SearchPane.GetForCurrentView().SuggestionsRequested += (s, e) =>
{
    if (e.QueryText.Length < 3)
        return;
    // TODO: if identical to the last request, return;
    // TODO: if asked less than 500ms ago, return;
};

<<p> 解决方案/strong>

System.Reactive.Linq.Observable.FromEventPattern<Windows.ApplicationModel.Search.SearchPaneSuggestionsRequestedEventArgs>
    (Windows.ApplicationModel.Search.SearchPane.GetForCurrentView(), "SuggestionsRequested")
    .Throttle(TimeSpan.FromMilliseconds(500), System.Reactive.Concurrency.Scheduler.CurrentThread)
    .Where(x => x.EventArgs.QueryText.Length > 3)
    .DistinctUntilChanged(x => x.EventArgs.QueryText.Trim())
    .Subscribe(x => HandleSuggestions(x.EventArgs));

安装RX for WinRT: http://nuget.org/packages/Rx-WinRT/了解更多信息:http://blogs.msdn.com/b/rxteam/archive/2012/08/15/reactive-extensions-v2-0-has-arrived.aspx

Answer 1

有Throttle和DistinctUntilChanged方法

System.Reactive.Linq.Observable.FromEventPattern<Windows.ApplicationModel.Search.SearchPaneSuggestionsRequestedEventArgs>
    (Windows.ApplicationModel.Search.SearchPane.GetForCurrentView(), "SuggestionsRequested")
    .Throttle(TimeSpan.FromMilliseconds(500), System.Reactive.Concurrency.Scheduler.CurrentThread)
    .Where(x => x.EventArgs.QueryText.Length > 3)
    .DistinctUntilChanged(x => x.EventArgs.QueryText.Trim())
    .Subscribe(x => HandleSuggestions(x.EventArgs));

您可能希望/需要为DistinctUntilChanged使用不同的过载，例如使用不同的相等比较器或Func<TSource, TKey>过载:

.DistinctUntilChanged(e => e.QueryText.Trim())