c# - 文件上传时 HttpPostedFileBase 始终为 null，模型绑定(bind)错误

Question

我正在尝试通过 JQuery Ajax 将文件上传到 ASP.NET Core MVC 应用程序。

HttpPostedFileBase 始终为 null。当我将其作为参数直接放入操作中时，我收到模型绑定(bind)错误。

Javascript:

$(document).on('click', '#attachItemBtn', function () {
    var attachItemFiles = document.getElementById('attachItemFile');

    var formData = new FormData();
    formData.append("Document", attachItemFiles.files[0]);
    formData.append("Id", 1234);
    formData.append("FileName", "test");

    $.ajax({
        cache: false,
        type: "POST",
        data: formData,
        processData: false,
        contentType: 'multipart/form-data',
        url: App.Urls.AddAttachment,
        success: function (data) {
            App.Messages.showErrorMessage('Item attached');
        },
        error: function (xhr, ajaxOptions, thrownError) {
            App.Messages.showErrorMessage('Error Occured While attaching document');
        }
    });

    var debug = 0;
});

行动:

[HttpPost]
public IActionResult AddAttachment(AttachmentItemModel model)
{
    var count = HttpContext.Request.Form.Files.Count;
    int i = 0;
    return Json("done");
}

型号:

public class AttachmentItemModel
{
    public int Id { get; set; }
    public HttpPostedFileBase Document { get; set; }
    public string FileName { get; set; }
}

上述代码适用于HttpContext.Request.Form.Files，但model.Document为null

当我将操作重写为以下函数签名时，出现错误:

public IActionResult AddAttachment(int Id, string FileName, System.Web.HttpPostedFileBase Document)

然后我收到以下错误:

An unhandled exception occurred while processing the request. InvalidOperationException: Could not create an instance of type 'System.Web.HttpPostedFileBase'. Model bound complex types must not be abstract or value types and must have a parameterless constructor.

我缺少什么？我希望将文件绑定(bind)在我的模型中，而不是使用 HttpContext.Request.Files。

Answer 1

你是如何让 HttpPostedFileBase 来解析的？无论如何，它在 ASP.NET Core 中不存在。相反，您应该使用 IFormFile。