ASP.net MVC上传图片NullReferenceException

Question

I've implemented simple create method to put data in database, and it worked fine. I've decided to add image upload, but I keep getting NullReferenceException (file is null) and I can't figure out why. I hope you can help me!

Here's my code:

[Authorize]
    public ActionResult Create()
    {
        ViewBag.CategoryId = new SelectList(_categoryRepository.GetAllCategories().AsEnumerable(), "CategoryId",
                                            "Name");
        return View();
    }

    //
    // POST: /Advert/Create

    [HttpPost, Authorize]
    public ActionResult Create(CompetitionDTO competitionDTO, HttpPostedFileBase file)
    {
        if (file.ContentLength > 0)
        {
            string fileName = Path.GetFileName(file.FileName);
            string fileExtension = Path.GetExtension(fileName);
            if ((fileExtension == ".jpg") || (fileExtension == ".png"))
            {
                string path = Path.Combine(Server.MapPath("~/Uploads/Images"), fileName);
                file.SaveAs(path);
                competitionDTO.ImageURL = path;
            }
        }
        if (ModelState.IsValid)
        {
            _competitionRepository.AddCompetition(competitionDTO, WebSecurity.CurrentUserId);


            return RedirectToAction("Index");
        }

        ViewBag.CompetitionId = new SelectList(_competitionRepository.GetAllCompetitions().AsEnumerable(),
                                               "CompetitionId", "Name");


        return View(competitionDTO);
    }
}

and View

<div>
        @using (Html.BeginForm("Create", "Competition", FormMethod.Post, new
            {
                enctype = "multipart/form-data"
                , id = "parentForm"
            }))
        {
            <input type="file" name="file" id="file"/>
            <input type="submit" value="Create" />
        }
    </div>

EDIT

I if I wasn't clear enough:

I know how to insert data to database and I know how to upload file, and I want when I click submit that those 2 things happen at same time

Answer 1

我有两个Html.BeginForms，这是我的错，现在我将它们合并为一个，并且效果很好