[HttpPost]
    public ActionResult Search (string[] jsonString)
    {
        IQueryable <UploadedFile> res = Context.UploadedFiles;
        if (!string.IsNullOrEmpty(jsonString[0]))
        {
            res = res.Where(x => x.FileTitle.Contains(jsonString[0]));
        }


        return View("UploadFilesView", res.ToList());
    }

res = res.Where(x => x.FileTitle.Contains(jsonString[0]));

var buffer = jsonString[0];

res = res.Where(x => x.FileTitle.Contains(buffer));