foreach on Request.Files

Question

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

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

The previous code generates this error:

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).

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

Answer 1

The enumerator on the HttpFileCollection returns the keys (names) of the files, not the HttpPostedFileBase objects. Once you get the key, use the Item ([]) property with the key (filename) to get the HttpPostedFileBase object.

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

    ...
}

Answer 2

The following code worked for me.

  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;
}

Answer 3

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

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 HttpFileCollectionBase implemented IEnumerable<HttpPostedFileBase> then we could do the foreach normally. However, it implements a non-generic IEnumerable.

Answer 4

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.

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.

HttpFileCollectionBase files = Request.Files;

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

    ...
}

Answer 5

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

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

Answer 6

With my tab HTML is:

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

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

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