编辑时上传控件返回 null

Question

我正在尝试创建一个 crud 应用程序，但每当我尝试在编辑模式下上传时，它都会返回 null。好吧，我不是第一次上传相同的文件，但我仅在编辑模式下上传。我首先上传两个文件，一个文件，另一个文件当时为空，另一个文件只会在编辑时上传模式，在那个时候第一个文件将是不可编辑的

public ActionResult Edit(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            FileDetails fileDetails = db.FileUpload.Find(id);
            if (fileDetails == null)
            {
                return HttpNotFound();
            }
            return View(fileDetails);
        }


        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Edit( FileDetails fileDetails)
        {
            if (ModelState.IsValid)
            {
                string uploadedfilename = Path.GetFileName(fileDetails.fileaftertourupload.FileName);
                if (!string.IsNullOrEmpty(uploadedfilename))
                {
                    string filenamewithoutextension = Path.GetFileNameWithoutExtension(fileDetails.fileaftertourupload.FileName);
                    string extension = Path.GetExtension(fileDetails.fileaftertourupload.FileName);
                    string filename = filenamewithoutextension + DateTime.Now.ToString("yymmssfff") + extension;
                    fileDetails.FileAfterTourName = filename;
                    fileDetails.FileAfterTour = "~/Content/Files/" + filename;
                    filename = Path.Combine(Server.MapPath("~/Content/Files"), filename);
                    fileDetails.fileaftertourupload.SaveAs(filename);

                    db.Entry(fileDetails).State = EntityState.Modified;
                    db.SaveChanges();
                    return RedirectToAction("Index");
                }
            }
            return View(fileDetails);
        }

@model OnlineStationaryRegister.Models.FileDetails

@{
    ViewBag.Title = "Edit";
}

<h2>Edit</h2>


@using (Html.BeginForm())
{
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <h4>FileDetails</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        @Html.HiddenFor(model => model.FileId)

        <div class="form-group">
            @Html.LabelFor(model => model.Officername, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Officername, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Officername, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Designation, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Designation, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Designation, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.FileBeforeTour, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                <a href="~/Content/Files/@Model.FileBeforeTourName" target="_blank">View File</a>

            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.FileAfterTour, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
              <input type="file" name="fileaftertourupload" />
            </div>
        </div>



        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Save" class="btn btn-default" />
            </div>
        </div>
    </div>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Web;

namespace OnlineStationaryRegister.Models
{
    public class FileDetails
    {
        [Key]
        public int FileId { get; set; }
        public string Officername { get; set; }
        public string Designation { get; set; }
        public string FileBeforeTour { get; set; }
        public string FileAfterTour { get; set; }
        public string FileBeforeTourName { get; set; }
        public string FileAfterTourName { get; set; }
        public int  status { get; set; } = 1;
        [NotMapped]
        public HttpPostedFileBase filebeforetourupload { get; set; }
        [NotMapped]
        public HttpPostedFileBase fileaftertourupload { get; set; }
    }
}

Answer 1

首先要上传图片，你应该在 beginform 中添加 enctype 属性。

@using (Html.BeginForm("FileUpload", "Home", FormMethod.Post, 
               new { enctype = "multipart/form-data" }))

接下来如果通过 multipart 发送多张图片，你应该得到字节 HttpContext.Current.Request.Files 在行动中。

Sample Code Upload Image by using asp.net mvc

How to Upload Image Via WebApi