Create a File in ASP.Net

Question

My web application wishes to send a file as an attachment to an email. That is quite doable; all I must do is specify the path to the file. But prior to sending the file, the system must create the file- it is a rendered report. It matters not where it is saved, since it will be in an attachment. That being the case, I cannot figure out how to write this file. It works on my localhost but not when I run it on our company's development server. The error message is a 500 one; undescriptive and unknown.

This is part of the event handler that transpires when a user clicks a button to generate a report which will get emailed to her boss:

In this code snippet, ext is some variable three letter file extension and content is content is the returned value of executing Render on a ReportExecutionService object:

var rptPath = HttpContext.Current.Server.MapPath(string.Format("Report.{0}", ext));
//using (var fs = new FileStream(rptPath, FileMode.OpenOrCreate, FileAccess.Write))
using (var fs = File.Create(rptPath))
{
    fs.Write(content, 0, content.Length);
}

...at this point it throws an Exception. I granted the NetworkService account write privileges via right-clicking on the file system of the development server and relaxing permissions to that account. I also relaxed security in IIS 6, which hosts the web application on the development server. What else needs to be done? I merely wish to spit a .pdf file to the root web directory.

Answer 1

ASP servers generally restrict what folders scripts are allowed to write in. Usually, an ASP application needs to have a dedicated folder configured with write access. Since you are specifying a relative file path to MapPath() without any leading slashes, it is going to return a full file path that is in the same folder as the calling .asp file, which is not likely to be writable within the script.

Answer 2

It works when I right click the folder and grant security permissions full access to the ASPNET account. It didn't work when I granted this to the NetworkService account, but it did when I granted to the ASPNET.

Answer 3

You could try using the System.IO.Path.GetTempFileName Method. "This creates a uniquely named, zero-byte temporary file on disk and returns the full path of that file." It creates it in the system temp diretcory, so you don't need to worry about clean-up etc.