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我想讓我的文件上傳代碼可選。此代碼返回由用戶處理的null reference exception
。文件上傳可選值
如何使其成爲可選的,如果用戶不選擇文件的空值應提交給數據庫?
這裏是控制器:
[HttpPost]
public ActionResult Create(AdulLiteracyTeachers adulliteracyteachers, HttpPostedFileBase[] files)
{
if (files.Length != null)
foreach (HttpPostedFileBase file in files)
{
string path = System.IO.Path.Combine(Server.MapPath("~/Content/Uploads/"), System.IO.Path.GetFileName(file.FileName));
if (System.IO.File.Exists(path))
{
ViewBag.Message = "File(s) Already Exist";
this.ModelState.AddModelError("", "Image with this Name Already Exist");
ViewBag.Error = TempData["Image with this Name Already Exist"];
}
else
{
file.SaveAs(path);
adulliteracyteachers.Image = file.FileName;
}
if (ModelState.IsValid)
{
db.AdulLiteracyTeachers.Add(adulliteracyteachers);
db.SaveChanges();
return RedirectToAction("Create");
}
}
ViewBag.DistID = new SelectList(db.Districts, "DistID", "DistName", adulliteracyteachers.DistID);
return View(adulliteracyteachers);
}
仍然得到了pRoblem對象引用未設置爲對象的實例。空引用異常由用戶解除 –