Ajax POST 抛出 500（内部服务器错误）

Question

我在 asp.net 核心应用程序中创建了一个弹出窗口，以使用 Ajax、jQuery 和引导程序来创建和编辑新书，但是当我在此表单中插入数据并在此处输入图像描述时出现此错误：

这是我在 Controller 中的 function

    [HttpPost]
    public IActionResult AddOrEdite(int id, BookViewModel bookViewModel)
    {
       

        if (!ModelState.IsValid)
        {

            if (id == 0)
            {
                string fileName = string.Empty;
                if (bookViewModel.File != null)
                {
                    string uploads = Path.Combine(hosting.WebRootPath, "uploads");
                    fileName = bookViewModel.File.FileName;
                    string fullPath = Path.Combine(uploads, fileName);
                    bookViewModel.File.CopyTo(new FileStream(fullPath, FileMode.Create));
                    bookViewModel.Book.imageURL = fileName;
                }
                if (!ModelState.IsValid)
                {
                    bookViewModel.Authors = _authorRepository.GetAll();
                    return View(bookViewModel);
                }
                Book book = new Book
                {
                    Bookid = bookViewModel.Book.Bookid,
                    Title = bookViewModel.Book.Title,
                    price = bookViewModel.Book.price,
                    Authorid = bookViewModel.Book.Authorid,
                    Borrowerid = bookViewModel.Book.Borrowerid,
                    Author = bookViewModel.Book.Author,
                    Borrower = bookViewModel.Book.Borrower,
                    imageURL = fileName
                };
                _bookRepository.Create(bookViewModel.Book);
            }
            else
            {
            
                bookViewModel.Authors = _authorRepository.GetAll();
                _bookRepository.Update(bookViewModel.Book);
            }


            return Json(new { isValid = true, html = GlobalClass.RenderRazorViewToString(this, "_ViewAllBook", _context.Books.ToList()) });
        }


        return Json(new { isValid = false, html = GlobalClass.RenderRazorViewToString(this, "AddOrEdit", bookViewModel) });
    }

这是我在 site.js 中的 function

 jQueryAjaxPost = form => { try { $.ajax({ type: 'POST', url: form.action, data: new FormData(form), contentType: false, processData: false, success: function (res) { if (res.isValid) { $('#view-all').html(res.html) $('#form-modal.modal-body').html(''); $('#form-modal.modal-title').html(''); $('#form-modal').modal('hide'); } else $('#form-modal.modal-body').html(res.html); }, error: function (err) { console.log(err) } }) return false; } catch (x) { console.log(x) }}

 @model BookViewModel @{ Layout = null; } <div class="row orderForm"> <form asp-controller="Book" asp-action="AddOrEdite" onsubmit="return jQueryAjaxPost(this);"> <input type="hidden" asp-for="@Model.Book.Bookid" /> <div class="form-group"> <label asp-for="Book.Author" class="col-md-2 control-label"></label> <div class="col-lg-12"> @Html.DropDownListFor(m => m.Book.Authorid, new SelectList(Model.Authors.Select(x => new { Value = x.AuthorId, Text = x.Name }), "Value", "Text"), "Select an author", htmlAttributes: new { @class = "form-control border-input" }) <span asp-validation-for="Book.Author" class="text-danger"></span> </div> <div class="col-lg-12 center"> <a class="btn btn-primary center" style="width:100%" asp-controller="Author" asp-action="Create">Create an author</a> </div> </div> <div class="row col-lg-12"> <div class="col-md-6"> <div class="form-group"> <label asp-for="Book.Title" class="col-lg-2 control-label"></label> <div> <input asp-for="Book.Title" class="form-control" placeholder="Enter book title" /> <span asp-validation-for="Book.Title" class="text-danger"></span> </div> </div> </div> <div class="col-md-6"> <div class="form-group"> <label asp-for="Book.price" class="col-lg-2 control-label"></label> <div> <input asp-for="Book.price" class="form-control" placeholder="Enter book title" /> <span asp-validation-for="Book.price" class="text-danger"></span> </div> </div> </div> </div> <div class="form-group"> <label asp-for="File" class="col-lg-2 control-label"></label> <div class="col-lg-12"> <input type="file" asp-for="File" class="form-control" placeholder="Enter Image of the book" /> <span asp-validation-for="File" class="text-danger"></span> </div> </div> <div class="form-group"> <div class="btn-group col-md-12"> <input class="btn btn-success center-block" type="submit" value="Create" /> </div> </div> </form> </div>

这是我的 model

    public class Book
{
    [Key]
    public int Bookid { get; set; }
    [Required,MinLength(2),MaxLength(200)]
    public string Title { get; set; }
    public int price { get; set; }
    public int Quantity { get; set; }
    public double Amount { get; set; }
    public string imageURL { get; set; }
    [ForeignKey("AuthorId")]
    public int Authorid { get; set; }
    public virtual Author Author { get; set; }

    [ForeignKey("CustomerId")]
    public int ? Borrowerid { get; set; }
    public virtual Customer Borrower { get; set; }


}

这是我的观点 model

  public class BookViewModel
{
    public Book Book { get; set; }
    public IEnumerable<Author> Authors { get; set; }
    [NotMapped]
    public IFormFile File { get; set; }
}

谁能帮帮我:(？

Answer 1

在我看来，当使用bookViewModel.Book时，您将在这里得到 null。

   if (!ModelState.IsValid)
    {

        if (id == 0)
        {
            string fileName = string.Empty;
            if (bookViewModel.File != null)
            {
                string uploads = Path.Combine(hosting.WebRootPath, "uploads");
                fileName = bookViewModel.File.FileName;
                string fullPath = Path.Combine(uploads, fileName);
                bookViewModel.File.CopyTo(new FileStream(fullPath, FileMode.Create));
                 
                // got null when bookViewModel.Book
                //bookViewModel.Book.imageURL = fileName;
                  if(bookViewModel.Book != null)
                     bookViewModel.Book.imageURL = fileName;
                 
            }
           ...

从代码中，我看不到form中的id 。 您可以尝试下面的controller代码。

[HttpPost]
public IActionResult AddOrEdite(BookViewModel bookViewModel)
{
   

    if (!ModelState.IsValid)
    {

        if (bookViewModel.Book.Bookid == 0) // or bookViewModel.id
        {