使用C＃和MVC3的HttpFileCollectionBase问题上传多个文件

Question

I created a controller which save files.

The below code is a part of that Controller:

if ( Request.Files.Count != 0 ) {
      HttpFileCollectionBase files = Request.Files;

      foreach ( HttpPostedFileBase file in files ) {
            if ( file.ContentLength > 0 ) {
               if ( !file.ContentType.Equals( "image/vnd.dwg" ) ) {
                  return RedirectToAction( "List" );
               }
            }
         }
 }

in ASPX page is simple:

<input type="file" name="file" />
<input type="file" name="file" />
...// many inputs type file

The problem is foreach because it returns an error like (I know because I run in Debug mode and placed breakpoint at foreach statement):

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

What is my mistake ?

Answer 1

Try like this:

[HttpPost]
public ActionResult Upload(IEnumerable<HttpPostedFileBase> files)
{
    if (files != null && files.Count() > 0)
    {
        foreach (var uploadedFile in files)
        {
            if (uploadedFile.ContentType != "image/vnd.dwg") 
            {
                return RedirectToAction("List");
            }

            var appData = Server.MapPath("~/app_data");
            var filename = Path.Combine(appData, Path.GetFileName(uploadedFile.FileName));
            uploadedFile.SaveAs(filename);                    
        }
    }

    return RedirectToAction("Success");
}

and modify the markup so that the file inputs are named files:

<input type="file" name="files" />
<input type="file" name="files" />
...// many inputs type file

Answer 2

for (int i = 0; i < Request.Files.Count; i++)
{
    var file = Request.Files[i];
    // this file's Type is HttpPostedFileBase which is in memory
}

HttpRequestBase.Files requires an index, so use for instead of foreach .

Answer 3

Have a look at this post by Phil Haack which demonstrates how to process multiple file uploads using MVC. The object you are trying to use is for ASP.NET Webforms.