I'm downloading text from a website and I want to have the user be able to save it as a file. So, I have the following code that does just that.
protected void DownloadFile(string fileName, string content)
{
Response.Clear();
Response.ClearContent();
Response.ClearHeaders();
Response.AddHeader("Content-Disposition", "attachment; filename=" + fileName);
Response.ContentType = "text/plain";
Response.Write(content);
Response.End();
}
The problem I am having is that I get an exception after this code runs. I believe it's due to the fact that I call Response.End(). So, every time a user downloads a file it redirects them to the generic error page because all generic exceptions redirect to that page.
Any ideas on how I can write text out to a file and not get this error? If I remove Response.End() I get my text and then the rest of the HttpResponse text, but I don't get the error.
Thanks.
First, if this code is inside a .ASPX file, you need to move it out to a .ASHX file.
Second, after you've moved to .ASHX you can simply write to the output stream and be done, you shouldn't need a Response.End();
This is the link I started with: http://dotnetperls.com/ashx-handler -- there isn't much to it. It simply removes a bunch of the asp.net "page" overhead.
Ideally you should have a page with a list, and a link/button to your "download.ashx" file. Then pass it a record id on the query string so it can do the lookup and response.write calls.
Don't call Response.End(). There is still code to be run server-side after you have populated the headers whether you intend to or not. Instead consider using Response.Flush() and allowing the page to complete. Another alternative would be to use a HttpHandler (ashx) file instead of an aspx/ascx file. This will give you more basic access to the Response so you should be able to end without repercussion.
Maybe you want to call Response.Output.Write() instead?
Related
I have a function in ASP that returns a TXT file.
I want the user to download the file but the browser wanted to keep displaying it when I did Response.Redirect("/Dir/Dir/TextFilePath.txt");
So I discovered that if you add this to the header it forces a download
Response.AddHeader("content-disposition",
"attachment;filename=/Dir/Dir/TextFilePath.txt");
And this DOES force download the file, with one catch.
The file is the aspx source code and not my txt file.... It's named correctly but it is most definitely not the txt file.
here is a correct way to download files in asp.net.
note the 'a correct way' and not 'the correct way', you can do it in other ways but this one works for me.
try
{
Response.Clear();
Response.ClearHeaders();
Response.ClearContent();
Response.AddHeader("content-disposition", "attachment; filename=" + _Filename);
Response.AddHeader("Content-Type", "application/Word");
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Length", _FileLength_in_bytes);
Response.BinaryWrite(_Filedata_bytes);
Response.End();
}
catch (ThreadAbortException)
{ }
finally
{
}
the example above transmits a word file by sending it as a byte array.
you dont have to do it this way, but it works.
also i would like to add for anyone who decides to use my method,
this WILL throw a ThreadAbortException at Response.End().
its a known issue and it affects nothing, everything is being executed correctly but the exception is still thrown, so it must be caught.
You can't affect the headers of the URL supplied for the redirect from the page where the redirect was issued from. I suspect that you actually want to do something like:
var responseText =
File.ReadAllText(Server.MapPath("~/Dir/Dir/TextFilePath.txt"));
Response.ContentType="text/plain";
Response.AddHeader("content-disposition",
"attachment;filename=TextFilePath.txt");
Response.Output.Write(responseText);
Response.End();
Have you tried something like this?
this.Response.AddHeader("content-disposition", "attachment;filename=" + file);
Response.TransmitFile( Server.MapPath(fileName) );
Response.End();
In one of our project we need the functionality to download a file from server to client location.
For this we are using an ashx handler to do the operation. Its working perfectly and we are able to download files.
Now we need a requirement like we need to update a field when a download is started and completed. Is there any way to do this.
Once we click the download link the Save as dialog box will appear and after that i think we don't have any control to check the progress. I think we even don't know which button is clicked ie we don't know whether the user is clicked a 'Yes' or 'No'.
Can anyone please suggest a method to know when the download is started and when it has been completed? We are using Asp.Net 2.0 with c#.
The handler used for download is given below
string fileUrl = string.Empty;
if (context.Request["fileUrl"] != null)
{
fileUrl = context.Request["fileUrl"].ToString();
}
string filename = System.IO.Path.GetFileName(fileUrl);
context.Response.ClearContent();
context.Response.ContentType = "application/exe";
context.Response.AddHeader("content-disposition", String.Format("attachment; filename={0}", filename));
context.Response.TransmitFile(fileUrl);
context.Response.Flush();
The file is downloaded from an aspx page method like
private void DownloadExe()
{
string downloadUrl = "Test.exe");
Response.Redirect("Test.ashx?fileUrl=" + downloadUrl, false);
}
Your ASHX handler knwos if download started (since it is actually get called) and when download is completed (end of handler is reached). You may even get some progress server side if you are writing response manually in chunks, this way you also may be able to detect some cases when user cancels download (if writing to response stream fails at some point).
Depending on your needs you may be able to transfer this information to other pages (i.e. via session state) or simply store in some database.
How about this:
Response.BufferOutput = false;
Response.TransmitFile(fileUrl);
//download complete code
If you disable response output buffering then it won't move past the line of code that sends the file to the client until the client has finished receiving it. If they cancel the download half way through it throws a HttpException so the download complete code doesn't get run.
You could also place your download complete code after your call to flush the buffer. But it's better not to enable buffering when sending large binary files to save on server memory.
Ok I had the same problem and jumped over this site:
Check over coockies
This works great for me.
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.
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.
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.
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.
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.)
the user clicks on a download button on WebForm1.aspx to start downloading a file. then, after the file download is done (served by WebForm2.aspx), user is automatically redirected.
WebForm1.aspx
<script type="text/javascript">
$(document).ready(function () {
$('#btnDL').click(function () {
$('body').append('<iframe src="WebForm2.aspx" style="display:none;"></iframe>');
return true;
});
});
</script>
<asp:Button runat="server" ID="btnDL" ClientIDMode="Static" Text="Download" OnClick="btnDL_Click" />
WebForm1.aspx.cs
protected void btnDL_Click(object sender, EventArgs e)
{
var sent = Session["sent"];
while (Session["sent"]==null)
{// not sure if this is a bad idea or what but my cpu is NOT going nuts
}
StartNextMethod();
Response.Redirect(URL);
}
WebForm2.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
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);
Session["sent"] = true;
}
Global.asax.cs
protected void Session_Start(object sender, EventArgs e)
{
Session["init"] = 0; // init and allocate session data storage
}
note: make sure don't use ashx (generic handler) to serve your download. for some reason, the session in ashx and aspx don't talk to each other, unless you implement this.
Just remove the context.Response.End(); because you are redirecting anyway...
The problem is flawed logic here.... Why would you end the response?
Get the PDF and display a link to it or use a META refresh to redirect to the location of the PDF or you could also display a link or use a combination of both techniques.
I believe what you are trying won't work.
This is what I would do:
Write content to a file locally and assign it an unique id
send user to the next page that contains a hidden frame that perform a request with the unique id (javascript)
hidden request page loads file and push on the content stream.
This is the same behavior a lot of file download sites is using. Only issue is if the hidden frame fails (javascript turned off) to perform the request, why a lot of the same sites have the link available if the auto request fails.
Disadvantage: file cleanup.
I recommend this solution :
Don't use response.End();
Declare this global var : bool isFileDownLoad;
Just after your (Response.BinaryWrite(a);) set ==> isFileDownLoad = true;
Override your Render like :
///
/// AEG : Very important to handle the thread aborted exception
///
///
override protected void Render(HtmlTextWriter w)
{
if (!isFileDownLoad) base.Render(w);
}
I have some files in a folder on the harddrive, like C:\ExtraContent\ that has some PDF files. This folder is not part of the website. I was able to successfully upload a PDF to this folder using the default ASP.NET FileUploader, no problem.
What I would like to do is, create a hyperlink that links to a PDF in that folder C:\ExtraContent\somePDF.pdf
I am able to get close using a Button with the following code:
protected void Button1_Click(object sender, EventArgs e)
{
WebClient client = new WebClient();
Byte[] buffer = client.DownloadData("C:\ExtraContent\somePDF.pdf");
Response.ContentType = "application/pdf";
Response.AddHeader("content-length", buffer.Length.ToString());
Response.BinaryWrite(buffer);
}
The above works in terms of opening the file. But I can't get this to work with an ASP.NET HyperLink.
The reason I want to use a HyperLink is so that the user can choose to right-click and Save As, to download a copy. If HyperLink controls can only link to relative paths, what can I do to get my desired result?
Note: making the files I'm trying to access part of the site is not practical for us.
Basically allowing access to the folder the way you describe is a real security risk (because it requires hacking at the permissions), isn't trivial and in general should be avoided. The way that you achieve your desired behaviour is something along these lines.
Firstly create a blank aspx or ashx page.
Secondly, either in the Page_Load or ProcessRequest you want to use code along the following lines
string filePath = "c:\\Documents\\Stuff\\";
string fileName = "myPath.pdf";
byte[] bytes = System.IO.File.ReadAllBytes(filePath + fileName);
context.Response.Clear();
context.Response.ContentType = "application/pdf";
context.Response.Cache.SetCacheability(HttpCacheability.Private);
context.Response.Expires = -1;
context.Response.Buffer = true;
context.Response.AddHeader("Content-Disposition", string.Format("{0};FileName=\"{1}\"", "attachment", fileName));
context.Response.BinaryWrite(bytes);
context.Response.End();
I haven't tested this and taken it from my head so it might need some tweeks but the above code should get you on the right track to cause the persons browser to begin downloading the file you provide.
EDIT: I just realized (after rereading your question) your problem was slightly different to what I thought, to get your issue resolved simply make the hyperlink button you are using link to a page that can process the request as described above. IE: An ashx or aspx page
You need to create a hyperlink to a page that acts as a 'proxy' so that the page will return a response that contains the file stream.
You cannot create a link to a file that is not prt of your site.
This code will always make my aspx page load twice. And this has nothing to do with AutoEventWireup.
Response.Clear();
Response.ContentType = "application/pdf";
Response.AppendHeader("Content-Disposition", "inline;filename=data.pdf");
Response.BufferOutput = true;
byte[] response = GetDocument(doclocation);
Response.AddHeader("Content-Length", response.Length.ToString());
Response.BinaryWrite(response);
Response.End();
This code will only make my page load once (as it should) when I hardcode some dummy values.
Response.Clear();
Response.ContentType = "application/pdf";
Response.AppendHeader("Content-Disposition", "inline;filename=data.pdf");
Response.BufferOutput = true;
byte[] response = new byte[] {10,11,12,13};
Response.AddHeader("Content-Length", response.Length.ToString());
Response.BinaryWrite(response);
Response.End();
I have also increased the request length for good measure in the web.config file.
<httpRuntime executionTimeout="180" maxRequestLength="400000"/>
Still nothing. Anyone see something I don't?
GetDocument(doclocation);
May be this method somehow returns Redirection code ? or may be an iframe or img for your dynamic content?
If so:
In general the control could get called twice because of the url response. First it renders the content. After that your browser tries to download the tag (iframe,img) source which is actually a dynamic content that is generated. So it makes another request to the web server. In that case another page object created which has a different viewstate, because it is a different Request.
Have you found a resolution to this yet? I having the same issue, my code is pretty much a mirror of yours. Main difference is my pdf is hosted in an IFrame.
So interesting clues I have found:
If I stream back a Word.doc it only gets loaded once, if pdf it gets loaded twice. Also, I have seen different behavior from different client desktops. I am thinking that Adobe version may have something to do with it.
Update:
In my case I was setting the HttpCacheability to NoCache. In verifying this, any of the non client cache options would cause the double download of the pdf. Only not setting it at all (defaults to Private) or explicitly setting it to Private or Public would fix the issue, all other settings duplicated the double load of the document.
Quick Guess: Could it be that at this stage in the page life cycle, the class that contains GetDocument() has already gone through garbage collection? The ASP.NET Worker process then needs to reload the page in order to read that method again?
Have you tried it in the Page_Load ? and why is GetDocument a static method?