gridview编辑行RegisterPostBackControl

Question

After much searching and testing, it's time to ask for opinions.
A GridView inside an Update Panel with a file upload in an EditItemTemplate:

 <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
     <asp:UpdatePanel ID="UpdatePanel1" runat="server">
         <ContentTemplate>
                    <asp:GridView ID="GridView1" runat="server" AllowPaging="True" AllowSorting="True"
                        AutoGenerateColumns="False" OnRowUpdating="GridView1_RowUpdating"
                        OnRowDataBound="GridView1_RowDataBound" OnRowEditing="GridView1_RowEditing"
                        OnRowCancelingEdit="GridView1_RowCancelingEdit" OnRowCommand="GridView1_RowCommand" >
                        <Columns>
                            <asp:CommandField ShowEditButton="True" ShowDeleteButton="true" >                                    
                            </asp:CommandField>
                            <asp:TemplateField HeaderText="Attachment" SortExpression="FileName">
                                <EditItemTemplate>
                                    <asp:FileUpload ID="FileUpload1" runat="server" /><br />
                                    <asp:Button ID="btnAddAttachment" runat="server" Text="Upload File" CommandName="AddAttachment"
                                        CommandArgument='<%# Bind("ID") %>' />
                                </EditItemTemplate>
                                <ItemTemplate>
                                    <a id="ancLink" runat="server" href='<%# "~/Files/" + (DataBinder.Eval(Container.DataItem,"FileName")) %>'
                                        target="_blank">
                                        <asp:Label ID="lblAnchor" runat="server"></asp:Label></a>
                                </ItemTemplate>
                            </asp:TemplateField>
                        </Columns>
                    </asp:GridView>
         </ContentTemplate>
     </asp:UpdatePanel>
 </asp:Content>

Then for the button in the EditItemTemplate, add the RegisterPostBackControl:

    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            if ((e.Row.RowState == DataControlRowState.Edit) || ((e.Row.RowState & DataControlRowState.Edit) > 0))
            {
                Button btnAddAttachment = (Button)e.Row.FindControl("btnAddAttachment");
                AjaxControlToolkit.ToolkitScriptManager ToolkitScriptManager1 = (AjaxControlToolkit.ToolkitScriptManager)Master.FindControl("ToolkitScriptManager1");
                ToolkitScriptManager1.RegisterPostBackControl(btnAddAttachment);
            }
        }
    }

The problem is that the RegisterPostBackControl will not work the first time an attempt is made to upload a file. If a user edits the same row again, the second attempt works fine.
Most likely because the RegisterPostBackControl takes effect on the second post back.
Is there a way to have the button have a full postback the first time?
I know there is an easy way for a work around but this defeats the purpose of the UpdatePanel:

     <Triggers>
         <asp:PostBackTrigger ControlID="GridView1" />
     </Triggers>

And since only Admins will have access to editing, setting the PostBackTrigger for the grid in the code behind for only admins is also an option, but once again, defeating the purpose of the Update Panel.
Any suggestions are welcome.

Answer 1

Depending on lots of factors, you could try the updatepannel option:

ChildrenAsTriggers="true"

It may work as a temporary workaround if you need to push something out now.

Answer 2

Based on your code you have the UpdatePanel using the default values so ChildrenAsTriggers is true and UpdateMode is Always, so you should get a full postback every time.

But I don't see you setting the Gridview's DataSourceID so it won't Databind unless you do so somewhere in the code behind. But you would have to be in edit mode initially in order to even find the control you're trying to register. So you need to register the control when you go into edit mode, try finding and registering the control in the gridview RowEditing event