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I have an application page in LAYOUTS in the 14 hive (SP 2010) within which I am dynamically appending HTML <input type="file"/> controls onto the page. Now when I try to post these files to the server to save them to a document library the HttpContext.Current.Request.Files collection is always empty.

Similar to this question: Sharepoint webpart upload file whitout[sic] using “runat server”

I can not use the <asp:FileUpload/> control with AllowMultiple set to true as there are many metadata input controls that are also being dynamically added to the page. I can not use a static amount of HTML file upload controls either; I have to add additional HTML file input controls client side.

I have found, from both the HttpRequest.Files Property MSDN page as well as various other places (like Request.Files is Empty in a Web Forms Application), that the HTML <form> elements encType value must be set to "multipart/form-data", which I am doing via:

protected void Page_Init(object sender, EventArgs e)
{
    Page.Form.Enctype = "multipart/form-data";
}

When debugging the page on post-back, the boundary=... section of the Request.ContentType value is appropriately being appended to the "multipart/form-data" value, but the HttpContext.Current.Request.Files collection is empty. (A nice explanation of the purpose of the boundary data is available in Scott Hanselman's blog post A Back To Basics Case Study: Implementing HTTP File Upload with ASP.NET MVC including Tests and Mocks). You can see the behavior I'm talking about in the debugger here:

HttpContext.Current.Request.Files Debug Info

Is this something to do with how requests are being handled for the Layouts directory? Or am I just missing something? Any help or pointers are greatly appreciated.

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You don't need to use Page.Form.Enctype = "multipart/form-data";.

When you are working with Application pages you have to use Page.Request.Files which gives you a HttpFileCollection object. This contains all files from all fileupload controls that has the runat="server" attribute on the page.

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  • Both collections are empty: Page.Request.Files and HttpContext.Current.Request.Files. The issue is that the input controls are dynamically added to the page client side so there is no runat="server" attribute. Normally in ASP.NET, the <input type="file"/> controls post their data to the server in a multipart request and can be accessed via the HttpRequest.Files collection, but this doesn't seem to be working. The documentation for HttpRequest.Files that I linked to above says: "The file collection is populated only when the HTTP request Content-Type value is 'multipart/form-data'." Commented Jul 2, 2014 at 15:38
  • @RJCuthbertson I have multiple working solutions where multipart/form-data is not anywhere on the page. If the input controls are dynamically added, by javascript I presume, what prevents you from having a javascript run afterwards which adds the runat="server" attribute? Commented Jul 2, 2014 at 16:57
  • Adding runat="server" client side doesn't do anything. It's just for the page parser, so that attribute needs to exist server side to actually have an effect. Commented Jul 2, 2014 at 18:03

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