Uploading Files in ASP.NET

Question

My web form creates Input file controls dynamically using javascript:

var input = document.createElement("input");
input.setAttribute("type", "file");
div.appendChild(input);

How do I get the "PostedFile" from these controls on the server side?

Answer 1

If it posts to the form with everything else then the contents should be in the Request.Files collection.

Answer 2

The Request.Files collection will contain any files that were posted.

Answer 3

If you prefer FileUpload control, you can generate few of the FileUpload controls on server (either through asp source with runat attribute or through application code) and hide them with css.

<asp:FileUpload ID="FileUpload1" runat="server" runat="server" class="hidden"/>

And then you can enable them with javascript after similar action as you would add new elements.

Then you can use the Files property of the Request object which returns a reference to the HttpFileCollection class. HttpFileCollection class has an Item property through which you get individual HttpPostedFile from the file collection either by specifying the name or index. See Listing 6 for an example.