How do I convert a file path to a URL in ASP.NET

Question

Basically I have some code to check a specific directory to see if an image is there and if so I want to assign a URL to the image to an ImageControl.

if (System.IO.Directory.Exists(photosLocation))
{
    string[] files = System.IO.Directory.GetFiles(photosLocation, "*.jpg");
    if (files.Length > 0)
    {
        // TODO: return the url of the first file found;
    }
}

Answer 1

this is what i use:

private string MapURL(string path)
{
    string appPath = Server.MapPath("/").ToLower();
    return string.Format("/{0}", path.ToLower().Replace(appPath, "").Replace(@"\", "/"));
 }

Answer 2

I think this should work. It might be off on the slashes. Not sure if they are needed or not.

string url = Request.ApplicationPath + "/" + photosLocation + "/" + files[0];

Answer 3

The problem with all these answers is that they do not take virtual directories into account.

Consider:

Site named "tempuri.com/" rooted at c:\domains\site
virtual directory "~/files" at c:\data\files
virtual directory "~/files/vip" at c:\data\VIPcust\files

So:

Server.MapPath("~/files/vip/readme.txt") 
  = "c:\data\VIPcust\files\readme.txt"

But there is no way to do this:

MagicResolve("c:\data\VIPcust\files\readme.txt") 
   = "http://tempuri.com/files/vip/readme.txt"

because there is no way to get a complete list of virtual directories.

Answer 4

I've accepted Fredriks answer as it appears to solve the problem with the least amount of effort however the Request object doesn't appear to conatin the ResolveUrl method. This can be accessed through the Page object or an Image control object:

myImage.ImageUrl = Page.ResolveUrl(photoURL);
myImage.ImageUrl = myImage.ResolveUrl(photoURL);

An alternative, if you are using a static class as I am, is to use the VirtualPathUtility:

myImage.ImageUrl = VirtualPathUtility.ToAbsolute(photoURL);

Answer 5

This worked for me:

HttpContext.Current.Request.Url.GetLeftPart(UriPartial.Authority) + HttpRuntime.AppDomainAppVirtualPath + "ImageName";

Answer 6

Maybe this is not the best way, but it works.

// Here is your path
String p = photosLocation + "whatever.jpg";

// Here is the page address
String pa = Page.Request.Url.AbsoluteUri;

// Take the page name    
String pn = Page.Request.Url.LocalPath;

// Here is the server address    
String sa = pa.Replace(pn, "");

// Take the physical location of the page    
String pl = Page.Request.PhysicalPath;

// Replace the backslash with slash in your path    
pl = pl.Replace("\\", "/");    
p = p.Replace("\\", "/");

// Root path     
String rp = pl.Replace(pn, "");

// Take out same path    
String final = p.Replace(rp, "");

// So your picture's address is    
String path = sa + final;

Edit: Ok, somebody marked as not helpful. Some explanation: take the physical path of the current page, split it into two parts: server and directory (like c:\inetpub\whatever.com\whatever) and page name (like /Whatever.aspx). The image's physical path should contain the server's path, so "substract" them, leaving only the image's path relative to the server's (like: \design\picture.jpg). Replace the backslashes with slashes and append it to the server's url.