Our problem/question revolves around an upload control that loses the selected file (goes blank) when a postback control is used (in this case, the dropdown list posts). Any insight into what we are doing wrong or how we can fix this? Below is our code and a summary of the problem.
Any help would be greatly appreciated.
Thank you!
<asp:updatepanel id="UpdatePanel1" runat="server">
<ContentTemplate>
<div class="
row">
<asp:DropDownList runat="server" AutoPostBack="true" ID="CategorySelection" OnSelectedIndexChanged="CategorySelection_IndexChanged" CssClass="drop-down-list" />
</div>
<div id="SubCategory" class="
row" runat="server" visible="false">
<asp:DropDownList runat="server" ID="SubCategorySelection" CssClass="drop-down-list" />
</div>
<div class="
row">
<asp:FileUpload runat="server" ID="FileUpload" CssClass="file-upload" />
</div>
<div class="
row">
<asp:Button ID="submit" runat="server" Text="Submit" CssClass="button" OnClick="submit_ButtonClick" />
</div>
</ContentTemplate>
<Triggers>
<asp:PostBackTrigger ControlID="submit" />
</Triggers>
</asp:updatepanel>
In this form we have 2 DropDownList, 1 FileUpload and 1 submit button. Every time that the user selects one category, the subcategories are loaded (AutoPostBack=”true”).
The primary user flow works fine: User selects one category, subcategory and selects a file to be uploaded (submitted). HOWEVER, if the user selects a file first, and then selects a category, the screen will do a partial refresh and the selected file will disappear (field goes blank). As a result, the user needs to select the file again. This causes an issue because the fact that the file is no longer selected can easily be overlooked.
Seems straighforward --- but causing us a lot of grief. Any experts out there that can help?
BIG thanks!
