Form with File Upload

Demo uploads land in a temporary store and are swept after 60 minutes. To keep files, handle FileUploaded — see Single File for the complete save pattern.

Embed AjaxFileUpload as a first-class form field alongside TextBox, DropDownList, and Button controls. The uploaded file ID is stored in a HiddenField and submitted with the postback - so the server-side FileUploaded event and the form Submit stay independent and both have everything they need. This pattern works equally well with any of the v5.3 transport strategies (classic, chunked, S3, Azure, GCS, tus) without changing the C# code.

What you should see: the uploader inside a bigger form: the file transfers out of band, its id lands in a hidden field, and the form submits independently.

Full Name

Category

Attachment

Drag & drop files here, or paste from clipboard

<asp:TextBox ID="txtName" runat="server" CssClass="form-control" />
<asp:DropDownList ID="ddlCategory" runat="server" CssClass="form-select">
 <asp:ListItem Text="General" Value="general" />
</asp:DropDownList>

<au:AjaxFileUpload ID="Uploader1" runat="server"
 AutoUpload="true"
 ShowProgress="true"
 OnClientUploadComplete="onFileUploaded" />
<asp:HiddenField ID="hdnFileId" runat="server" />

<asp:Button ID="BtnSubmit" runat="server" Text="Submit"
 CssClass="btn btn-primary" OnClick="BtnSubmit_Click" />