文件存在总是返回false

Question

ImageURL = String.Format(@"../Uploads/docs/{0}/Logo.jpg", SellerID);
if (!File.Exists(ImageURL))
{
    ImageURL = String.Format(@"../Uploads/docs/defaultLogo.jpg", SellerID);
}

Everytime I check if there is file, I get the default logo in image, is there something beyond permission to check.

Note: this is class library referenced on website

Answer 1

You have to give physical path instead of virtual path (url) you can use webRequest to find if file exists on given url . You can read this article to see different methods for check if resource at given url exists.

private bool RemoteFileExists(string url)
{
    try
    {
        //Creating the HttpWebRequest
        HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
        //Setting the Request method HEAD, you can also use GET too.
        request.Method = "HEAD";
        //Getting the Web Response.
        HttpWebResponse response = request.GetResponse() as HttpWebResponse;
        //Returns TURE if the Status code == 200
        return (response.StatusCode == HttpStatusCode.OK);
    }
    catch
    {
        //Any exception will returns false.
        return false;
    }
}

Edit based on comments, running the code on server hosting the files accessed by url . I assume your upload folder is on root of web site directory.

ImageURL = String.Format(@"/Uploads/docs/{0}/Logo.jpg", SellerID);
if(!File.Exists(System.Web.Hosting.HostingEnvironment.MapPath(ImageURL))
{

}

Answer 2

If this is within a web application, the current directory is usually not what you think it is. For example if IIS is serving the web pages, the current directory may be where inetsrv.exe is or a temp directory. To get the path to your web application you can use

string path = HostingEnvironment.MapPath(@"../Uploads/docs/defaultLogo.jpg");
bool fileExists = File.Exists(path);

http://msdn.microsoft.com/en-us/library/system.web.hosting.hostingenvironment.mappath.aspx

MapPath will convert the path you give it into something relative to your web application. To make sure path is being set correctly you can use trace debugging with Trace.Write or write the path to a debug file (using an absolute path for the debug file).