Upload Default File Path if field is empty

Thanks a lot!!! It works...... Great Thanks again

 [HttpPost] 
            [ValidateAntiForgeryToken] 
            public ActionResult CreateContacts(Contact contacts, HttpPostedFileBase ImageFile)/*,TAG2,FLEX1,FLEX2,FLEX3*/ 
            { 
                            
                if (ModelState.IsValid) 
                { 
if( ImageFile != null && ImageFile.FileName != "")
{
                    string fileName = Path.GetFileNameWithoutExtension(ImageFile.FileName); 
                    string extension = Path.GetExtension(ImageFile.FileName); 
                    fileName = fileName + DateTime.Now.ToString("yymmssfff") + extension; 
                    contacts.PhotoID = "~/Uploads/UploadImages/" + fileName; 
                    fileName = Path.Combine(Server.MapPath("~/Uploads/UploadImages/"), fileName); 
                    ImageFile.SaveAs(fileName);
}
else
{
 contacts.PhotoID = "~/Uploads/UploadImages/Guest.PNG";
}
 
     
                    using (ESContext db = new ESContext()) 
                    { 
                        db.Contacts.Add(contacts); 
                        db.SaveChanges(); 
                        return RedirectToAction("IndexContacts"); 
                    } 
     
                    } 
              
     
                return View(contacts); 
            }