C# 在 Request.Files 上 foreach

foreach on Request.Files

提问by Omar

I'm attempting upload multiple files in ASP.NET MVC and I have this simple foreach loop in my controller

我正在尝试在 ASP.NET MVC 中上传多个文件，并且我的控制器中有这个简单的 foreach 循环

foreach (HttpPostedFileBase f in Request.Files)
{
    if (f.ContentLength > 0)
        FileUpload(f);
}

The previous code generates this error:

前面的代码生成此错误：

Unable to cast object of type 'System.String' to type 'System.Web.HttpPostedFile'. 

What I don't understand is why Request.Files[1] returns an HttpPostedFileBase but when it's iterated over, it returns strings (presumably the file names).

我不明白的是为什么 Request.Files[1] 返回一个 HttpPostedFileBase 但是当它被迭代时，它返回字符串（大概是文件名）。

Note: I know this can be solved with a for loop. Also, I tried using HttpPostedFile, with the same error.

注意：我知道这可以用 for 循环解决。另外，我尝试使用 HttpPostedFile，但出现相同的错误。

采纳答案by tvanfosson

The enumerator on the HttpFileCollectionreturns the keys (names) of the files, not the HttpPostedFileBaseobjects. Once you get the key, use the Item([]) property with the key (filename) to get the HttpPostedFileBaseobject.

上的枚举器HttpFileCollection返回文件的键（名称），而不是HttpPostedFileBase对象。获得密钥后，使用Item( []) 属性和密钥（文件名）来获取HttpPostedFileBase对象。

foreach (string fileName in Request.Files)
{
    HttpPostedFileBase file = Request.Files[fileName];

    ...
}

回答by Joe Barone

You might try iterating the strings and casting them to HttpPostedFile instead, like this:

您可以尝试迭代字符串并将它们转换为 HttpPostedFile，如下所示：

foreach (string file in Request.Files)
    {
        HttpPostedFile hFile = Request.Files[file] as HttpPostedFile;
        if (hFile.ContentLength > 0)
            FileUpload(hFile);
    }

回答by Harvey

Unfortunately tvanfosson's answer did not work for me. Although the files would upload just fine, and no error would be thrown, a problem would occur where only one of the files would be used, so the same file would be saved twice rather than using them both.

不幸的是，tvanfosson 的回答对我不起作用。虽然文件上传得很好，不会抛出错误，但会出现一个问题，只使用一个文件，所以同一个文件会保存两次，而不是同时使用它们。

It seemed to be a problem with the foreach statement looping through the names of each file in the Request.Files, for some reason it wasn't working as a key for me, and only the first file would be selected every time.

循环遍历 Request.Files 中每个文件的名称的 foreach 语句似乎有问题，出于某种原因，它对我来说不是一个键，每次只会选择第一个文件。

HttpFileCollectionBase files = Request.Files;

for(var i = 0; i < files.Count; i++)
{
    HttpPostedFileBase file = files[i];

    ...
}

回答by nguyenhoai890

With my tab HTML is:

我的标签 HTML 是：

<input class="valid" id="file" name="file" multiple="" type="file">

Request.Files will have duplicate name in array. So you should solve like this:

Request.Files 将在数组中具有重复名称。所以你应该这样解决：

for (int i = 0; i < Request.Files.Count; i++ ){
    HttpPostedFileBase fileUpload = Request.Files[i];

回答by Ivan DCosta

The following code worked for me.

以下代码对我有用。

  HttpResponseMessage result = null;
  var httpRequest = System.Web.HttpContext.Current.Request;
  HttpFileCollection uploadFiles = httpRequest.Files;
  var docfiles = new List<string>();

  if (httpRequest.Files.Count > 0){
      int i;
      for (i = 0; i < uploadFiles.Count; i++) {
          HttpPostedFile postedFile = uploadFiles[i];
          var filePath = @"C:/inetpub/wwwroot/test1/reports/" + postedFile.FileName;
          postedFile.SaveAs(filePath);
          docfiles.Add(filePath);
      }
      result = Request.CreateResponse(HttpStatusCode.Created, docfiles);
  } else {
      result = Request.CreateResponse(HttpStatusCode.BadRequest);
  }

  return result;
}

回答by Akira Yamamoto

We can use LINQ to do this and still use foreach as asked:

我们可以使用 LINQ 来做到这一点，并且仍然按照要求使用 foreach：

var files = Enumerable.Range(0, Request.Files.Count)
    .Select(i => Request.Files[i]);

foreach (var file in files)
{
    // file.FileName
}

As @tvanfosson said, the enumerator returns the file names as strings, not the HttpPostedFileBase. This method HttpPostedFileBase this[string name]returns the object we want. If HttpFileCollectionBaseimplemented IEnumerable<HttpPostedFileBase>then we could do the foreach normally. However, it implements a non-generic IEnumerable.

正如@tvanfosson 所说，枚举器将文件名作为字符串返回，而不是HttpPostedFileBase. 这个方法HttpPostedFileBase this[string name]返回我们想要的对象。如果HttpFileCollectionBase实现，IEnumerable<HttpPostedFileBase>那么我们可以正常执行 foreach。但是，它实现了一个非通用的IEnumerable.

回答by Jnr

You can get the HttpPostedFileout of the HttpFileCollectionusing foreachlike this:

您可以像这样HttpPostedFile停止HttpFileCollection使用foreach：

foreach (var obj in fileCollection)
{
    HttpPostedFile file = fileCollection.Get(obj.ToString());
}