IFormFile在ASP.NETCore3.1MVC中始終為空

我已經坐在辦公桌前好幾天了，閱讀谷歌搜索，試圖讓我的 ASP.Net Core 應用程式將檔案上傳到物理位置，并將檔案名存盤在資料庫中。但是，每當我嘗試上傳檔案時，IFormFile 總是回傳 null。我對此很陌生。

這是查看代碼

<div >
    <form method="post" enctype="multipart/form-data" asp-controller="Quiz" asp-action="Create"  >
        <div asp-validation-summary="ModelOnly" ></div>
        
        <div >
            <label asp-for="QuizTitle" ></label>
            <input asp-for="QuizTitle"  />
            <span asp-validation-for="QuizTitle" ></span>
        </div>
        <div >
            <label asp-for="Category" ></label>
            <input asp-for="Category"  />
            <span asp-validation-for="Category" ></span>
        </div>
        <div >
            <label asp-for="Author" ></label>
            <input asp-for="Author"  />
            <span asp-validation-for="Author" ></span>
        </div>
        <div >
            <label asp-for="QuizPdf" ></label>
            <input asp-for="QuizPdf" >
            <span asp-validation-for="QuizPdf" ></span>
            </div>
        
        <div >
            <input type="submit" value="Create"  />
        </div>
    </form>

控制器代碼

public IActionResult Create()
    {
        return View();
    }

    // POST: Quiz/Create
    // To protect from overposting attacks, enable the specific properties you want to bind to.
    // For more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
    [HttpPost]
    [ValidateAntiForgeryToken]

    public async Task<IActionResult> Create([FromForm]IFormFile PostedFile, QuizDetailsModel quizDetailsModel)
    {
        if (ModelState.IsValid)
        {
            if (quizDetailsModel.QuizPdf != null)
            {
                string folder = "files/pdfs/";
                folder  = quizDetailsModel.QuizPdf.FileName;

                quizDetailsModel.QuizPdfUrl = folder;

                string serverFolder = Path.Combine(_webHostEnvironment.WebRootPath, folder);

                await quizDetailsModel.QuizPdf.CopyToAsync(new FileStream(serverFolder, FileMode.Create));
            }
            _context.Add(quizDetailsModel);
            await _context.SaveChangesAsync();
            return RedirectToAction(nameof(Index));
        }
        return View(quizDetailsModel);
    }

和型號代碼

public class QuizDetailsModel
{
    public int Id { get; set; }
    [Required(ErrorMessage = "Please enter a quiz title.")]
    [Display(Name = "Title")]
    public string QuizTitle { get; set; }
    [Required(ErrorMessage = "Please select a category.")]
    public string Category { get; set; }
    [Required(ErrorMessage = "Please enter a quiz author")]
    public string Author { get; set; }
    [Display(Name = "Upload quiz pdf.")]
    [Required]
    [NotMapped]
    public IFormFile? QuizPdf { get; set; }
    public string QuizPdfUrl { get; set; }
    [Display(Name = "Date Added")]
    [DisplayFormat(DataFormatString = "{0:MMMM dd, yyyy")]
    [DataType(DataType.Date)]
    public DateTime DateAdded { get; set; } = DateTime.Now;

    public List<QuestionsAnswersModel> QuestionsAnswers { get; set; } = new List<QuestionsAnswersModel>();

選項 2：在創建視圖中，添加 type="file", method="post" enctype="multipart/form-data"

      <form asp-action="Create"  method="post" enctype="multipart/form-data" >
            <div asp-validation-summary="ModelOnly" ></div>
                ...
            <div >
                <label asp-for="QuizPdf" ></label>
                <input asp-for="QuizPdf" type="file" />
                <span asp-validation-for="QuizPdf" ></span>
            </div>
                   ...
             <div >
                <input type="submit" value="Create"  />
            </div>
        </form>

結果：

uj5u.com熱心網友回復：

引數被呼叫PostedFile，欄位名被呼叫QuizPdf你認為它們是一樣的嗎？

更新您的代碼，如下所示。洗掉[FromForm]不需要這個，并將您的引數名稱更改PostedFile為QuizPdf

public async Task<IActionResult> Create(IFormFile QuizPdf , QuizDetailsModel quizDetailsModel)

{

  //clarify code

}

它肯定會解決你的問題。

標籤：asp.net 核心

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