How can I get the user response regarding SaveFileDialog in Javascript? - asp.net

The following code is implemented in Page_Load event to show SaveFileDialog to the user
string targetFileName = Request.PhysicalApplicationPath + "Reports\\TempReports\\FolderMasters" + Utility.GetRandomNumber() + ".pdf";
FileInfo file = new FileInfo(targetFileName);
// Clear the content of the response.
Response.ClearContent();
Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);
Response.AddHeader("Content-Length", file.Length.ToString());
Response.ContentType = "application/pdf";
Response.TransmitFile(file.FullName);
Response.End();
How can I get the user response to SaveFileDialog, as I need to know user response to this dialog?
Also, is there something wrong with these lines of code, as I had the following exception
"Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack."

You can't get the user response to SaveFileDialog as all file-events have been blocked for browser-javascript as it could be a very big security-hole ...

I'm here again, as I got a solution for my second question.
For Response.End, call the HttpContext.Current.ApplicationInstance.CompleteRequest method instead of Response.End to bypass the code execution to the Application_EndRequest event.
Have look ...

Related

download code expalanation in asp.net

can anyone please explain this code
if (e.CommandName == "download")
{
string filename = e.CommandArgument.ToString();
string path = MapPath("~/Docfiles/" + filename);
byte[] bts = System.IO.File.ReadAllBytes(path);
Response.Clear();
Response.ClearHeaders();
Response.AddHeader("Content-Type", "Application/octet-stream");
Response.AddHeader("Content-Length", bts.Length.ToString());
Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
Response.BinaryWrite(bts);
Response.Flush();
Response.End();
}
what is command argument, mappath, and also what is this
"Content-Type", "Application/octet-stream"
and also
Response.AddHeader("Content-Length", bts.Length.ToString());
Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
Response.BinaryWrite(bts);
Response.Flush();
First, I advise you to use the MSDN documentation to search for more information about the objects and methods you wanna know more about. MSDN is a useful network and should be used.
Quoting the MSDN CommandArgument : "Gets or sets an optional parameter passed to the Command event along with the associated CommandName". It is used to get an parameter that was passed to the command event. In this case, it was the file name.
string filename = e.CommandArgument.ToString();
The MapPath is used to map a specified path to a physical path. Using this you get the real path of the file. For example: "C:\Docfiles\Yourfile.pdf"
string path = MapPath("~/Docfiles/" + filename);
The ReadAllBytes method, opens a file, reads the content and then closes the file. This return the content of this file as a byte array.
byte[] bts = System.IO.File.ReadAllBytes(path);
The Response object is used to send output to the user from the server.
Response.Clear();
Response.ClearHeaders();
Response.AddHeader is used to build the header of response that will be sent back to user. We use it to set infos about the data we are sending back to the client.
The "Content-Type" attribute is used to especify what kind of file you are returning to the user.
Response.AddHeader("Content-Type", "Application/octet-stream");
The "Content-Length" attribute is used to inform to the browser the size of the the file you are returning.
Response.AddHeader("Content-Length", bts.Length.ToString());
The "Content-Disposition" is used to inform the name of the file that will be returned. For example "file1.doc"
Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
The "BinaryWrite()" write your file (who, at this moment, is in a byte array format) to the current HTTP output without any character conversion.
Response.BinaryWrite(bts);
The Flush method sends buffered output immediately.
Response.Flush();
And, finally, causes the server to stop processing the request and return the current result.
Response.End();
If the command is download, most likely from a grid button, then get the name of the file as the argument (these are properties on a button control), and send it to the browser. This prompts the user to download the file.

Response.End() throwing an Error

In my application I need to download a file, So I am using this piece of code:
Response.ContentType = "application/octet-stream";
Response.AppendHeader("Content-Disposition", "attachment; filename =" + strFileName + ".xls");
Response.TransmitFile(strFilePath);
Response.End();
at Response.End() i am getting an error ThreadAbortException
To aviod this error I am trying to use httpApplication.CompleteRequest(),
but i m not able to use this too.
The code with httpApplication.CompleteRequest() is below,
Response.ContentType = "application/octet-stream";
Response.AppendHeader("Content-Disposition", "attachment; filename =" + strFileName + ".xls");
Response.TransmitFile(strFilePath);
HttpApplication.CompleteRequest();
I m getting this error when i m using HttpApplication.CompleteRequest()
An object reference is required for the non-static field, method, or property 'System.Web.HttpApplication.CompleteRequest()'
I hope i m able to make my doubt clear...
help me out....
Response.End() is expected to throw a ThreadAbortException.
This is by design, so that the rest of the page response is not processed.
It is perfectly ok to get this exception, and it will ensure the page is not processed further.
Refer: HttpResponse.End
The CompleteRequest method does not raise an exception, and code after
the call to the CompleteRequest method might be executed. If your
intention is to avoid execution of subsequent code, and if the
performance penalty of End is acceptable, you can call End instead of
CompleteRequest.
Try this code:
Response.ContentType = "application/octet-stream";
Response.AppendHeader("Content-Disposition", "attachment; filename =" + strFileName + ".xls");
Response.TransmitFile(strFilePath);
HttpContext.Current.ApplicationInstance.CompleteRequest();
The error occures because you are using a ASP update panel or any control using JavaScript. Try to use control native from ASP or HTML without JavaScript or ScriptManager or scripting.
I have experienced this problem and have solved it with the following code
ScriptManager sm = ScriptManager.GetCurrent(this.Page);
sm.RegisterPostBackControl(this.grid);
Just comment this line and you're good to go:
//Response.End();
It worked for me :)

TransmitFile continue with page_load efter Response.End

I've been looking for an answer for a week now and I give up.
I'm creating an excelfile and then let the user download it to his client with TransmitFile.
The thing is, this works perfectly most of the time, but in some cases (can be repeated), after the Response.End, the page reloads and page_load is called. The flag IsPostBack is false.
This behaviour interrupt the download and the whole application stop working, displaying connecting to server.
foreach (string filename in Directory.GetFiles(WebConfigurationManager.AppSettings.Get("EXCEL_PATH")))
{
if (File.GetLastWriteTime(filename) < (DateTime.Now.AddDays(-1)))
{
File.Delete(filename);
}
}
ClsOrderFormData ofData = new ClsOrderFormData(ddOrderTypes.SelectedValue, OF.Customer.CustomerCategory);
ClsExportOF xls = new ClsExportOF(OF.SizeDims, ofData, OF.Customer, Request.PhysicalApplicationPath, ClsPrintOrder.getOrderData().TheOrder.Articles);
string sFileName = xls.CreateExcelFile();
FileInfo OutFile = new FileInfo(WebConfigurationManager.AppSettings.Get("EXCEL_PATH") + sFileName);
Response.Clear();
Response.AddHeader("content-disposition", "attachment; filename=Abacus_OF_" + ddOrderTypes.SelectedItem.Text + "_" + ddCustomer.SelectedItem.Text + "_" + DateTime.Now.ToShortDateString() + ".xls".Replace(',', '-'));
Response.ContentType = "application/vnd.ms-excel";
Response.TransmitFile(WebConfigurationManager.AppSettings.Get("EXCEL_PATH") + sFileName, 0, OutFile.Length);
Response.Flush();
Response.End();
In short. When it works no more code is executed after Response.End(), as expected. When it don't work it continue with page_load and so on, and the site hangs.
Any tips?
Trying using HttpApplication.CompleteRequest instead of Response.End. Response.End is probably throwing a ThreadAbortException which is messing up the process.
see...
http://ardalis.com/Use-HttpApplication.CompleteRequest-Instead-of-Response.End
http://weblogs.asp.net/hajan/archive/2010/09/26/why-not-to-use-httpresponse-close-and-httpresponse-end.aspx

ASP.Net Transmit File

I am writing a webapplication in ASP.net.
I am trying to make a file dialog box appear for downloading something off the server.
I have the appropriate file data stored in a variable called file.
File has fields:
FileType - The MIMEType of the file
FilePath - The server-side file path
Here's the code so far:
Response.Clear();
Response.ContentType = file.FileType;
Response.AppendHeader("Content-Disposition", "attachment; filename=" + GetFileName(file));
Response.TransmitFile(file.FilePath) ;
Response.End();
GetFileName is a function that gets me the filename from an attachment object. I only store the path.
The above code is in a function called "Download_Clicked" that is an event that triggers on click. The event is mapped to a LinkButton.
The problem is that when I run the above code, nothing happens. The standard dialog box does not appear.
I have attempted the standard trouble-shooting such as making sure the file exists, and ensuring the path is correct. They are both dead on the mark.
My guess is that because my machine is also the server, it may not be processing properly somehow.
Thanks in advance.
Edit 1: Attempted putting control onto another page, works fine.
Edit 2: Resolved issue by removing control from AJAX Update Panel.
I've found another to do this without removing the update panel. Place the code below in your page load and you'll now be able to use that button to trigger a download.
ScriptManager.GetCurrent(this.Page).RegisterPostBackControl(Button);
Use Response.WriteFile() instead.
Also, don't use Response.End()! This aborts the thread. Use Response.Flush(); Response.Close();
Try changing
Response.AppendHeader("Content-Disposition", "attachment; filename=" + GetFileName(file));
To
Response.AppendHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(GetFileName(file))));
If that doesn't work, you can always use Response.BinaryWrite or Resonse.Write to stream the file to the web browser
Here is how transmit the file using Response.Write or Response.BinaryWrite. Put these functions in a library somewhere then call them as needed
public void SendFileToBrowser(String FileName, String MIMEType, String FileData)
{
Response.Clear();
Response.AddHeader("Content-Disposition", "attachment; filename=" + FileName);
Response.ContentType = MIMEType;
Response.Buffer = true;
Response.Write(FileData);
Response.End();
}
public void SendFileToBrowser(String FileName, String MIMEType, Byte[] FileData)
{
Response.Clear();
Response.AddHeader("Content-Disposition", "attachment; filename=" + FileName);
Response.ContentType = MIMEType;
Response.Buffer = true;
Response.BinaryWrite(FileData);
Response.End();
}
Then somewhere you call these functions like so
SendFileToBrowser("FileName.txt", "text/plain", "Don't try this from an Update Panel. MSAjax does not like it when you mess with the response stream.");
See edit on initial post.
Removed Ajax Update Panel to resolve the error. The panel was stopping the post back to the server.
For more info, see Cris Valenzuela's comment.

How to send a file to a client so a Download dialog will open?

I have a file, say a PDF on my website and when a user visits a page I want to display a download dialog for the pdf on page load or a button click.
I did a google search and I found two ways to do this but wondering what is the accepted way of doing this? I am currently doing this
string pdfPath = MapPath("mypdf.pdf");
Response.ContentType = "Application/pdf";
Response.AppendHeader( "content-disposition",
"attachment; filename=" + name );
Response.WriteFile(pdfPath);
Response.End();
(Code was based off code from http://aspalliance.com/259, also found code from
http://www.west-wind.com/weblog/posts/76293.aspx)
Your code, will display the file to the user perfectly. But they will have to use the "Save As" option to actually save it.
If you wish to present the "Save Dialog" to the user, try the following:
string pdfPath = MapPath("mypdf.pdf");
Response.ContentType = "Application/pdf";
Response.AppendHeader("content-disposition",
"attachment; filename=" + pdfPath );
Response.TransmitFile(pdfPath);
Response.End();
This of course assumes the file actually exists on the server and is not being dynamically generated.
This code will Send Any file to directly on client Browser
Response.ContentType = "application/pdf";
Response.WriteFile(PathToFile);
Response.Flush();

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