ASP.NET 4.5异步等待和Response.Redirect [英] ASP.NET 4.5 async-await and Response.Redirect

问题描述

使用async-await时是否有任何方法可以从Page_Load(或任何其他ASP.NET事件)重定向?当然，Redirect会抛出ThreadAbortException，但是即使我用try-catch捕获它，它最终也会出现错误页面.如果我调用Response("url", false)，它不会崩溃，但是我需要停止执行页面(渲染页面等)，所以这不是解决方案.正如我注意到的，这两种方法的行为有所不同:

Is there any way to redirect from Page_Load (or any other ASP.NET event) when using async-await? Of course Redirect throws ThreadAbortException but even if I catch it with try-catch it ends up with an error page. If I call Response("url", false) it doesn't crash but I need to stop execution of the page (rendering the page etc.) so it's not the solution. And as I noticed these two methods act differently:

这以ThreadAbortException结尾(我假设任务同步结束):

This ends up with ThreadAbortException (I assume the task ends synchronously):

protected async void Page_Load()
{
    await Task.Run(() => { });
    Response.Redirect("http://www.google.com/");
}

此响应在Response.Redirect之后继续进行:

This one continues after Response.Redirect:

protected async void Page_Load()
{
    await Task.Delay(1000);
    Response.Redirect("http://www.google.com/");
}

我必须等待响应，但是我正在尝试，即使删除了await关键字(因此Task在后台运行并且该方法继续)，其结果也相同.唯一有用的是删除async关键字-我认为async仅启用await，仅此而已?！

I must wait for the response but I was experimenting and even if I remove the await keyword (so Task runs in background and the method continues) it ends up the same. Only thing that helps is to remove the async keyword - I thought async ONLY enables await and nothing more?!

推荐答案

好的，我找到了如何处理它的答案.

OK, I found the answer how to deal with it.

我已经在我的基Page类中创建了一个Redirect方法包装器:

I've created a Redirect method wrapper in my base Page class:

protected void Redirect(string url)
{
    this.isRedirecting = true;

    Response.Redirect(url, false);

    if (Context.ApplicationInstance != null)
        Context.ApplicationInstance.CompleteRequest();
}

并覆盖Render和RaisePostBackEvent:

protected override void Render(HtmlTextWriter writer)
{
    if (this.isRedirecting)
        return;
}

protected override void RaisePostBackEvent(IPostBackEventHandler sourceControl, string eventArgument)
{
    if (!this.isRedirecting)
        base.RaisePostBackEvent(sourceControl, eventArgument);
}

就可以了.在所有等待的任务完成之前，ASP.NET 4.5不会触发PreRenderComplete事件(=在生命周期中不会继续).

That does the trick. ASP.NET 4.5 won't fire the PreRenderComplete event (= won't continue in the life-cycle) until all awaited tasks are completed.

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