I want to allow my user to click on a button that says "download" and then will build a dynamic csv file on the fly and will prompt the user to download. I know how to build the file using a HTTPHandler, but not quite sure the mechanism for delivering the content via download.
I usually create a Generic Handler (.ashx) and do something like this:
public void ProcessRequest(HttpContext context)
{
StringBuilder myCsv = new StringBuilder();
foreach(myRow r in myRows) {
myCsv.AppendFormat("\"{0}\",{1}", r.MyCol1, r.MyCol2);
}
context.Response.ContentType = "application/csv";
context.Response.AddHeader("content-disposition", "attachment; filename=myfile.csv");
context.Response.Write(myCsv.ToString());
}
Now if the CSV you're building is REALLY big, you might want to write out each row as you create it, rather than stuffing it into a StringBuilder.
Just emit a Content-Disposition HTTP header in your HTTP Handler code. Most browsers will interpret that as a download request. Replace yourfile.csv by the filename you want the user to see.
context.Response.ContentType = "text/csv";
context.Response.AddHeader("Content-Disposition", "attachment; filename=yourfile.csv");
Related
Could anyone please tell me how could I stream a pdf to a new tab browser? I just have the pdf stream on memory and I want when I click over the link to show the PDF in a new tab or window browser.
How could I do that?
Thank!!!
I have this link:
<a id="hrefPdf" runat="server" href="#" target="_blank"><asp:Literal ID="PdfName" runat="server"></asp:Literal></a>
In my code behind I have this on the onload event:
Stream pdf= getPdf
if (pdf != null)
{
SetLinkPDF(pdf);
}
private void SetLinkPDF(IFile pdf)
{
hrefPdf.href = "MyPDF to the Browser"
PdfName.Text = pdf.PdfName;
}
Someway I have to process the stream pdf (IFile contains Name, Stream,Metadata, etc of the PDF)
What can I do to proccess this and whe I click show the stream at a new browser?
I have another probelm, is not working the OnClientClick="aspnetForm.target='_blank';" timbck2 suggested me. I have to open the file (image or pdf ) in a new window, what could I do? Is not working this. Thank!
Timbbck2 my asp code is:
<asp:LinkButton runat="server" ID="LinkButtonFile" OnClick="LinkButtonFile_Click" OnClientClick="aspnetForm.target = '_blank';"></asp:LinkButton>
Thanks!!!
I've done this from a file on disk - sending the data from a memory stream shouldn't be that much different. You need to supply two pieces of metadata to the browser, in addition to the data itself. First you need to supply the MIME type of the data (in your case it would be application/pdf), then the size of the data in bytes (integer) in a Content-Length header, then send the data itself.
So in summary (taking into account the comments and what I think you're asking, your markup would look like this:
<asp:LinkButton ID="whatever" runat="server" OnClick="lnkButton_Click"
OnClientClick="aspnetForm.target='_blank';">your link text</aspnet:LinkButton>
These few lines of C# code in your code behind should do the trick (more or less):
protected void lnkButton_Click(object sender, EventArgs e)
{
Response.ClearContent();
Response.ContentType = "application/pdf";
Response.AddHeader("Content-Disposition", "inline; filename=" + docName);
Response.AddHeader("Content-Length", docSize.ToString());
Response.BinaryWrite((byte[])docStream);
Response.End();
}
To display pdf directly in the browser you should set content type for the response to application/pdf
Your user should also have some kind of pdf reader installed for this to work.
Did you try Response.BinaryWrite?? You probably want to set some headers as well.
The top answer suggests converting (casting) a stream to a byte[] first, that will download the file to the server (from whatever stream it is coming from) and then send it to the client.
If you need to provide a Stream as a parameter for some external service (like me for Azure Storage) you can use the following method.
public ActionResult Coupons(string file)
{
Response.AddHeader("Content-Disposition", "inline; filename=" + file);
Response.ContentType = "application/pdf";
AzureStorage.DownloadFile(file, Response.OutputStream);//second parameters asks for a 'Stream', you can use whatever stream you want here, just put it in the Response.OutputStream
return new EmptyResult();
}
That will Stream the file to the client directly (as far as I know).
I need the browser to open file types it understands directly in the browser (i.e. no "Open/Save/Cancel" dialog.
Here's my code, which currently works great!...except that every file pops up the dialog box and doesn't directly open the file:
string filePath = Path.Combine(WebConfigurationManager.AppSettings["NewsAttachmentPath"], context.Request.QueryString["FileName"]);
byte[] bytes = System.IO.File.ReadAllBytes(filePath);
context.Response.Clear();
context.Response.ContentType = "application/octet-stream";
context.Response.Cache.SetCacheability(HttpCacheability.Private);
context.Response.Expires = -1;
context.Response.Buffer = true;
context.Response.AddHeader("Content-Disposition", string.Format("{0};FileName=\"{1}\"", "inline", context.Request.QueryString["FileName"]));
context.Response.BinaryWrite(bytes);
context.Response.End();
As you can see, even when I change the Content-Disposition to "inline", it still prompts for download. This is with files that I know my browser understands. In other words, I can go to some random site and click a PDF, and it will open in the browser. My site will make me save it in order to view it.
Pre-emptive answer to "why do you wanna use application/octet-stream?" Because I don't want to create a handler for each single file type. If this is mistaken, please let me know.
You do not need to create a handler per file type. You just change the line:
context.Response.ContentType = "application/octet-stream";
to be:
string contentType = //your logic here, possibly many lines in a separate method
context.Response.ContentType = contentType;
But no: you can't "inline" an application/octet-stream. That means "here's some bytes, but I don't know what they are". The browser can't do much with that, other than save it somewhere, hence a download prompt. You can use content-disposition to suggest a filename, though.
The browser does not work on file extensions - it works on content-type. So: you need to report the correct content-type in your response. This might mean writing a switch / lookup based on the file extension that you know, or it might mean storing the explicit content-type separately as metadata along with the file information.
I have an ASP.NET page where a user provides an ID, and then we pull some data from the DB and put it into an Excel spreadsheet. I would like to create the Excel file in memory and then allow the user to download the file. I could create a file on the server, and then delete it afterwards, but it seems unnecessary. Depending on error handling I could potentially orphan a file with that approach, etc.
Is something like this possible? Or do I need to use a file stream?
On a side note, I'm using EPPlus as an API (quick plug for it).
You want to specify the content-type and content-dispisition headers like so - Response.ContentType = "application/vnd.ms-excel" works in IE and firefox but not in Safari, then stream your file. Once complete, call Response.End() to stop the application execution
Code Sample:
void StreamExcelFile(byte[] bytes)
{
Response.Clear();
Response.ContentType = "application/force-download";
Response.AddHeader("content-disposition", "attachment; filename=name_you_file.xls");
Response.BinaryWrite(bytes);
Response.End();
}
ExcelPackage pck = new ExcelPackage();
.....
.....
.....
byte[] bfr = pck.GetAsByteArray();
Response.ContentType = "application/application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
Response.AppendHeader("content-disposition", "attachment; filename=ExcelFileName.xlsx");
Response.OutputStream.Write(bfr, 0, bfr.Length);
Response.Flush();
Response.Close();
Yes, look into using an HTTP Handler to stream the file to the browser from memory.
http://msdn.microsoft.com/en-us/library/ms972953.aspx
What you're looking for is called a generic handler:
http://www.dotnetperls.com/ashx
In a nutshell, what you need to do is define the context type. Which in your case will be a xls or xlsx. Set the response, and direct the user to the handler.
They will be prompted to download the file.
basically below is the code for me to read pdf file, the output for this code below is ask client to download the pdf file and open it from client side, this is not what i want,what i want it open the pdf at another browswer windows or open in inside tag under same browser windows, but how can i make it?
var fi = new FileInfo(Server.MapPath(#"~/AIA2.pdf"));
Response.Clear();
Response.AddHeader("Content-Disposition",
String.Format("attachment; filename=\"{0}\"",
"AIA2.pdf"));
Response.AddHeader("Content-Length", fi.Length.ToString());
Response.ContentType = "application/octet-stream";
Response.WriteFile(fi.FullName);
Response.End();
This is not upto the server to decide how content is handled - content disposition could be set to attachment or inline but its to the handling application to process these and i do not think any browser does that.
I can suggest a two step solution for this:
Use inline; instead of attachment
On the client side (if you have control on that ofcourse), use something like
That should do the trick!
hi there i am working on an asp.net web page that first lets users to enter required values to indicated textfields and then generate a new text file according to the data given by the user.
I want to let users receive a "Result.xml" file when they click on "get file" button.
i've searched for that info, i know it must have an easy solution but by now i am out of luck (i must be tired). i tried the following code but it didnt worked:
DataSet ds = new DataSet();
ds.Tables.Add("TEST");
ds.writexml("test.xml");
Response.TransmitFile("test.xml");
but the program says it couldnt find any file. also i dont want to "write" a physical file to the server, i just want to send the contents of the dataset as "test.xml"
Please help,
Thanks for spending your time.
Well assuming you are able to populate your DataSet properly, you should be able to use DataSet.WriteXML as in your example to write to a MemoryStream, then dump the file to the HTTP response without ever hitting your server's disk.
I'm a little rusty with C#, this example is from VB, so please take syntax with a grain of salt:
System.IO.MemoryStream objStream = new System.IO.MemoryStream();
System.Data.DataSet ds = new System.Data.DataSet();
ds.Tables.Add("TEST");
ds.WriteXml(objStream);
Response.Clear();
Response.Buffer = true;
Response.ContentType = "text/xml";
Response.AddHeader("Content-Disposition", "attachment; filename=File.xml");
Response.BinaryWrite(objStream.ToArray());
Response.End();
You can use the below code to write a XML file to the Client machine. Here we
write the contents directly into the Response.OutputStream using the XmlTextWriter:
try
{
Response.Clear();
Response.ContentType = "text/xml";
Response.AppendHeader("Content-Disposition","attachment;filename=FileName.xml");
XmlTextWriter xWriter = new XmlTextWriter(Response.OutputStream, System.Text.Encoding.UTF8);
xWriter.Formatting = Formatting.Indented;
xWriter.WriteStartDocument();
//Create Parent element
xWriter.WriteStartElement("Parent");
//Create Child elements
xWriter.WriteStartElement("Element");
xWriter.WriteElementString("ID", "1001");
xWriter.WriteElementString("Name", "John");
xWriter.WriteElementString("Age", "22");
xWriter.WriteEndElement();
//End writing top element and XML document
xWriter.WriteEndElement();
xWriter.WriteEndDocument();
xWriter.Close();
Response.End();
}
Whenever you work with files in Asp.Net you should use Server.MapPath. If you use relative paths your code will probably try to write to the IIS folder and might (hopefully) not be allowed to do so. So instead of using "test.xml" you should use
Server.MapPath("~/text.xml")
The tilde expands to your web application folder. That said it's a bad idea to store the file to disc. The Response object has an OutputStream which can be used to send data to the browser. You should write your data set directly into that stream. So no file has to be written to disc, you don't have to care about paths and your code will also work with multiple concurrent requests.
You can have the link link to an IHTTPHandler with the folowing code:
public class YourHandler : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
Response.Clear();
Response.ContentType = "text/xml";
Response.AppendHeader("Content-Disposition", String.Format("attachment;filename={0}", XML_FileName));
Response.TransmitFile(Server.MapPath("MyFile.xml"));
Response.End();
}
public bool IsReusable
{
get
{
return false;
}
}
}