ASP.Net check if FileUpload control is empty

Question

Hello,

I am using LINQ to retrieve data from the DataBase, the variable name relative to link is "service".

the upDocument is the Id of a FileUpload control.

The objective is to delete the old file, before uploading a new one. This is the code i came up with:

if ((service.image_url != null || service.image_url != "") &&
    (upDocument.FileName.Length != 0 || upDocument.PostedFile.ToString() != ""))
{
     if (File.Exists(System.Web.HttpContext.Current.Server.MapPath(service.image_url)))
     {
          File.Delete(System.Web.HttpContext.Current.Server.MapPath(service.image_url));
     }
}

The problem that I have, is that althought nothing is being loaded to the FileUpload the file is still being deleted. I made a breakpoint and checked it out... and contraty to what i was expecting the FileName.Length is not 0, and the postedFile.ToString() is not "".

How can i make a correct validation?

Thanks in advance.

Answer 1

Check the HasFile property, like this:

if (!String.IsNullOrEmpty(service.image_url) && upDocument.HasFile) { 
    if (File.Exists(Server.MapPath(service.image_url)))
        File.Delete(Server.MapPath(service.image_url));
}

By the way, inside an ASP.Net page, you don't need to write System.Web.HttpContext.Current, so you can simply write Server.MapPath.

Answer 2

Your problem is that you're deleting the file if service.image_url is null OR if it's "". That condition will always be true, since it can't be both null and "" at the same time.

You should write !String.IsNullOrEmpty(service.image_url), as I wrote in my first answer.