I will try to simplify my situation here to be more clean and concise. So, I am working on a WinRT application where user enters text in a TextBox and in its TextChanged event after 2 seconds have elapsed I need to make a remote request to fetch data based on user text.
Now user enters text and a web request has been initialized but immediately user writes another term. So, I need to cancel the first web request and fire the new one.
Consider the following as my code :
private CancellationTokenSource cts;
public HomePageViewModel()
{
cts = new CancellationTokenSource();
}
private async void SearchPeopleTextChangedHandler(SearchPeopleTextChangedEventArgs e)
{
//Cancel previous request before making new one
//GetMembers() is using simple HttpClient to PostAsync() and get response
var members = await _myService.GetMembers(someId, cts.Token);
//other stuff based on members
}
I know CancellationToken plays a role here but I just cannot figure out how.
あなたはすでにほとんどそれを持っています。基本的な考え方は、シングルCancellationTokenSourceは1回しかキャンセルできないため、操作ごとに新しいものを作成する必要があるということです。
private CancellationTokenSource cts;
private async void SearchPeopleTextChangedHandler(SearchPeopleTextChangedEventArgs e)
{
// If there's a previous request, cancel it.
if (cts != null)
cts.Cancel();
// Create a CTS for this request.
cts = new CancellationTokenSource();
try
{
var members = await _myService.GetMembers(someId, cts.Token);
//other stuff based on members
}
catch (OperationCanceledException)
{
// This happens if this operation was cancelled.
}
}
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