public WebResult AddSharing(int ownerId, int friendId, string folder)
        {
            WebResult result = new WebResult();

            var owner = (from u in db.Users where u.id == ownerId select u).SingleOrDefault();
            var friend = (from u in db.Users where u.id == friendId select u).SingleOrDefault();

            if (owner == null || friend == null)
                return new WebResult(WebResult.ErrorCodeList.USER_NOT_FOUND);
            string path = System.IO.Path.Combine(HttpContext.Current.Server.MapPath("~"), "upload_files", owner.username, folder);
            if (System.IO.Directory.Exists(path))
            {
                Sharing share = new Sharing()
                {
                    folder = folder,
                    idOwner = owner.id,
                    idRecevier = friendId,
                    user = owner.username
                };
                db.Sharings.InsertOnSubmit(share);
                db.SubmitChanges();
            }
            else
                return new WebResult(WebResult.ErrorCodeList.DIRECTORY_NOT_FOUND);
            return result;
        }
 partial void UpdateSharing(Sharing instance);
 partial void DeleteSharing(Sharing instance);
 partial void InsertSharing(Sharing instance);