How not to abort http response c#

Question

I need to run several methods after sending file to a user for a download. What happens is that after I send a file to a user, response is aborted and I can no longer do anything after response.end().

for example, this is my sample code:

 Response.Clear();
 Response.AddHeader("content-disposition", "attachment;  filename=test.pdf");
 Response.ContentType = "application/pdf";
 byte[] a = System.Text.Encoding.UTF8.GetBytes("test");
 Response.BinaryWrite(a);
 Response.End();
 StartNextMethod();
 Response.Redirect(URL);

So, in this example StartNextMethod and Response.Redirect are not executing.

What I tried is I created a separate handler(ashx) with the following code:

public void ProcessRequest(HttpContext context)
        {
            context.Response.Clear();
            context.Response.AddHeader("content-disposition", "attachment;  filename=test.pdf");
            context.Response.ContentType = "application/pdf";
            byte[] a = System.Text.Encoding.UTF8.GetBytes("test");
            context.Response.BinaryWrite(a);
            context.Response.End();
        }

and call it like this:

Download d = new Download();
d.ProcessRequest(HttpContext.Current);
StartNextMethod();
Response.Redirect(URL);

but the same error happen. I've tryied to replace Response.End with CompleteRequest but it doesn't help.

I guess the problem is that I'm using HttpContext.Current but should use a separate response stream. Is that correct? how do I do that in a separate method generically (Assume that I want my handler to accept byte array of data and content type and be downloadable from a separate response. I really do not want to use a separate page for a response.

UPDATE
I still didn't find a good solution. I'd like to do some actions after user has downloaded a file, but without using a separate page for a response\request thing.

Answer 1

Update
Since you said no second page, do this instead. Add a section to your page that checks for a query string parameter (something like fileid, or path, etc...). If this value is present then it initiates the download process using your existing code. If this value is not present then it runs like normal.

Now when the user clicks the download link you perform a post back (which you are already doing). In this post back create an iFrame on the page and set the URL of the iFrame to your pages URL with the added query string parameter (mypage.aspx?id=12664 or ?download=true, something like that). After creating the iframe perform what ever additional databinds/etc... you wish too.

Example
- http://encosia.com/ajax-file-downloads-and-iframes/

This above linked example uses an iFrame and an update panel, just like you are talking about.

Original Post
Response.Flush will allow you to continue processing after you send the file to the user, or just don't call Response.End (you don't really need too).

However Daniel A. White is correct, you can't actually redirect from your code after you send a file, you will get an error if you try. BUT you can continue to perform other server side operations if you need to.

Other answers agree with the general consensus, you can't redirect after a file starts downloading: https://stackoverflow.com/a/822732/328968 (PHP, but same concepts since it involves HTTP in general). or Directing to a new page after downloading a file.

Answer 2

Response.End() throws a thread abort exception. It is designed to end your response. No code after that will process in that thread.

The End method causes the Web server to stop processing the script and return the current result. The remaining contents of the file are not processed.

What is it that you are trying to achieve?

If your purpose it to allow the pdf to download and then take the user to some other page, a little javascript can help you out.

Add a script with a timer to set location.href to your redirected paged.

Answer 3

As the previous answers had stated - returning PDF file means to send HTTP headers. You cannot send another headers after that, and Response.Redirect() simply means to send HTTP 302.

If you don't want to have separate page, or if you don't want to use AJAX, why not trying:

<head>
    <meta http-equiv="refresh" content="3; url=http://www.site.com/download.aspx?xxxx">
</head>

Actually this will show the desired page you want to show to the user, and will refresh the page after 3 sec with the URL for download of the PDF file.

Answer 4

Download the file in chunks, as illustrated File Download in ASP.NET and Tracking the Status of Success/Failure of Download or in the answer to this question. When the last chunk of the file has been written to the client you can execute the code you need to. (Doesn't have to be at the end, can be anywhere in between depending upon your needs.)