In ASP.NET, how to get the browser to download string content into a file? (C#)

Question

I would like to create a text file for export/download, like a *.csv, from an ASP.NET application. I know about Response.TransmitFile, but I want to do this without creating

Answer 1

You'll want to look at writing a Custom HTTP Handler (a class that implements IHttpHandler) and simply register it in web.config. See this article on MSDN for a good example of how to set one up.

Here's a basic example of how you might go about implementing one to return the markup for some CSV data.

using System.Web;

public class MyCsvDocumentHandler : IHttpHandler
{
    public static string Data
    {
        get;
        set;
    }

    public MyCsvDocumentHandler()
    {
    }

    public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "text/csv"; // Set the MIME type.
        context.Response.Write(Data); // Write the CSV data to the respone stream.
    }

    public bool IsReusable
    {
        // To enable pooling, return true here.
        // This keeps the handler in memory.
        get { return false; }
    }
}

This alternative, which is possibly slightly simpler, is to use an ASHX handler page. The code would be almost identical.