为什么MVC HttpPostedFileBase始终为空？ [英] Why is MVC HttpPostedFileBase always null?

问题描述

这是我的观点

测试上传档案

 < ; form action =@ Url.Action（Index，Home）method =postenctype =multipart / form-data> 
 @ Html.AntiForgeryToken（）
< label for =file>文件名：< / label> 
< input type =filename =filesid =files/> 
 
< input type =submitname =submitvalue =Upload/> 
< / form> 
  

这是我的控制器

 public Valid ActionResult Index（IEnumerable< HttpPostedFileBase> files）
 {
 if（files！= null）
 {
 foreach（var file in files）
 {
 try 
 {
 if（file！= null&& file.ContentLength> 0）
 {
 var fileName = file.FileName; 
 var path = Path.Combine（Server.MapPath（@\Upload），fileName）; 
 file.SaveAs（path）; 
 
 ViewBag.Message =文件上传成功; 
 
 $ b $ catch（Exception ex）
 {
 ViewBag.Message =ERROR：+ ex.Message.ToString（）; 
} 
} 
} 
 return View（）; 
} 
  

问题是HttpPostedFileBase文件始终为空。我无法找到问题。

< img src =https://i.stack.imgur.com/VR0fx.pngalt =在这里输入图片描述>

解决


$ b

> postenctype =multipart / form-data>

< label for =file>档案名称：< / label>
< input type =filename =filesid =files/>

< input type =submitname =submitvalue =Upload/>
< / form>

脚本

 < script type =text / javascript> 
 var form = document.getElementById（'formTest'）。onsubmit = function（e）{
 e.preventDefault（）; 
 var formdata = new FormData（）; // FormData对象
 var fileInput = document.getElementById（'files'）; 
 if（fileInput！=&& fileInput.files.length> 0）{
 //遍历fileInput中选定的每个文件
 for（i = 0; i< ; fileInput.files.length; i ++）{
 //将每个文件附加到FormData对象
 formdata.append（fileInput.files [i] .name，fileInput.files [i]）; 
 
 //创建一个XMLHttpRequest并发送
 var xhr = new XMLHttpRequest（）; 
 
 var url ='@ Url.Action（Index，Home）'; 
 xhr.open（'POST'，url）; 
 xhr.send（formdata）; 
 xhr.onreadystatechange = function（）{
 if（xhr.readyState == 4&&xhr.status == 200）{
 var result = xhr.responseText; 
 
} 
} 
 return false; 
} 
} 
< / script> 
  

C＃
$ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ if $
{
var file = Request.Files [0];
if（file！= null&& file.ContentLength> 0）
{
var fileName = Path.GetFileName（file.FileName）;
var path = Path.Combine（Server.MapPath（〜/ Images /），fileName）;
file.SaveAs（path）;
}
return View（）;

}
}

This is my View

Test Upload File

<form action="@Url.Action("Index", "Home")" method="post" enctype="multipart/form-data">
    @Html.AntiForgeryToken()
    <label for="file">Filename:</label>
    <input type="file" name="files" id="files" />

    <input type="submit" name="submit" value="Upload" />
</form>

This is my Controller

 [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Index(IEnumerable<HttpPostedFileBase> files)
          { 
              if (files != null)
                {
                 foreach (var file in files)
                   {
                    try
                     {
                      if (file != null && file.ContentLength > 0)
                        {
                          var fileName = file.FileName;
                          var path = Path.Combine(Server.MapPath(@"\Upload"), fileName);
                          file.SaveAs(path);

                          ViewBag.Message = "File uploaded successfully";
                         }
                       }
                      catch (Exception ex)
                      {
                        ViewBag.Message = "ERROR:" + ex.Message.ToString();
                       }
                   }
                 }
               return View();
             }

The problem is the HttpPostedFileBase files is always null. I cant find the problem.

解决方案

Here is an example how to use form onsubmit method

Your HTML part

<form id="formTest" method="post" enctype="multipart/form-data">

        <label for="file">Filename:</label>
        <input type="file" name="files" id="files" />

        <input type="submit" name="submit" value="Upload" />
    </form>

script

<script type="text/javascript">
var form = document.getElementById('formTest').onsubmit = function (e) {
        e.preventDefault();
    var formdata = new FormData(); //FormData object
    var fileInput = document.getElementById('files');
    if (fileInput != "" && fileInput.files.length > 0) {
        //Iterating through each files selected in fileInput
        for (i = 0; i < fileInput.files.length; i++) {
            //Appending each file to FormData object
            formdata.append(fileInput.files[i].name, fileInput.files[i]);
        }
        //Creating an XMLHttpRequest and sending
        var xhr = new XMLHttpRequest();

           var url = '@Url.Action("Index","Home")';
        xhr.open('POST', url);
        xhr.send(formdata);
        xhr.onreadystatechange = function () {
            if (xhr.readyState == 4 && xhr.status == 200) {
                var result = xhr.responseText;

            }
        }
        return false;
    }
}
</script>

C#

public ActionResult Index()
{ 
   if (Request.Files.Count > 0)
   {
      var file = Request.Files[0];    
      if (file != null && file.ContentLength > 0)
      {
         var fileName = Path.GetFileName(file.FileName);
         var path = Path.Combine(Server.MapPath("~/Images/"), fileName);
         file.SaveAs(path);
      }
    return View();

   }
}

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