How to assign UpdatePanel Trigger’s control ID with button’s from gridview

asp.netgridviewtriggersupdatepanel

currently I have a UpdatePanel for jQuery Dialog use, which contains a GridView.

And that GridView contains a FileUpload control in footer and EmptyDataTemplate

In order to get FileUpload control work in javascript, I know that we need trigger.

However, the button that I wanna assign as trigger is inside GridView's template…

when the button btnAdd clicked, file in FileUpload control will be saved.

Here is the code:

<asp:UpdatePanel ID="upnlEditExpense" runat="server">
      <Triggers>
            <asp:AsyncPostBackTrigger ControlID="btnAdd"/>
      </Triggers>
            ......................
                 ........................
                       .........................
      <asp:GridView runat="server" ID="grdExpense" ShowHeader="True" ShowFooter="True"
           AutoGenerateColumns="False">
           <Columns>
                 ...................
                 <asp:TemplateField>
                       <FooterTemplate>
                              <asp:LinkButton runat="server" ID="btnAdd" Text="Add" OnClick="btnAdd_Click"></asp:LinkButton>
                       </FooterTemplate>
                 </asp:TemplateField>
           </Columns>
      </asp:GridView>
</asp:UpdatePanel>

If I put the button id directly in trigger's control ID like this, error come up saying btnAdd could not be found…

what should I do to get FileUpload control work?

Best Answer

This works

protected void grdExpense_RowCreated(object sender, GridViewRowEventArgs e)
    {
        LinkButton btnAdd = (LinkButton)e.Row.Cells[0].FindControl("btnAdd");
        if (btnAdd != null)
        {
            ScriptManager.GetCurrent(this).RegisterPostBackControl(btnAdd);
        }

    }

Related Solutions

C# – Dynamically Add Footer to ASP.NET GridView

You're partially right -- the dynamically added controls don't exist anymore after the postback. They won't get re-added until the DataBound event is run. The problem is that Databinding events happen after control events, that is, after your button's Click event. So, at the point in the page lifecycle where the click event is handled, those controls haven't been recreated yet.

Here's a related question which might have some useful information.

How to configure a GridView CommandField to trigger Full Page Update in UpdatePanel

To register a control as a trigger for a postback, use ScriptManager's RegisterPostBackControl Method.

     If editLink IsNot Nothing Then
           ScriptManager.GetCurrent(this.Page).RegisterPostBackControl(editLink )
        End If

This methods works too for controls dynamically added within other controls. I had the same problem with my GridView. I've registered linkButton and imageButton of a TemplatedField row.

I use RowCreated Gridview's handler instead of RowDataBound handler : RowCreated is focused on parsing Gridview row's definition and creating the Gridview row's control structure, RowDataBound is focused on bind data to the row's controls created in the RowCreated. Also RowCreated is invoked automatically in both init and postback case, but RowDataBound is only invoke when the DataBind is called. Code

<asp:GridView ID="ContactsGridView" runat="server" AutoGenerateColumns="False"
        DataSourceID="ContactsContainerDataSource" EnableViewState="false"
        DataKeyNames="CompanyID,ContactId" AllowSorting="True" AllowPaging="true"
        OnRowCreated="ContactsGridView_RowCreated" PageSize="10" CssClass="GridSimple"
        OnRowCommand="ContactsGridView_RowCommand">
        <Columns>
               <asp:TemplateField HeaderStyle-CssClass="large" HeaderText="Contact" SortExpression="ContactNom">
                <ItemTemplate>
                    <asp:ImageButton ID="PreviewImageButton" runat="server" ImageUrl="../images/picto_pdf.gif"
                        CommandName="PreviewContact" CommandArgument=<%#Eval("ContactCode") %> BorderWidth="0"
                        ToolTip="View Pdf Document" />
                    <asp:LinkButton ID="ContactNamePreviewLinkButton" runat="server" CommandName="Select"
                        CommandArgument='<%#Eval("ContactCode") %>'><%#Eval("ContactName")%></asp:LinkButton>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>




    protected void ContactsGridView_RowCreated(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            //Register download buttons as PostBack controls  (instead of AsyncPostback because of their updatepanel container))
            ImageButton ib = (ImageButton)e.Row.FindControl("PreviewImageButton");
            if (ib != null) ScriptManager.GetCurrent(this.Page).RegisterPostBackControl(ib);
            LinkButton lb = (LinkButton)e.Row.FindControl("ContactNamePreviewLinkButton");
            if (lb != null) ScriptManager.GetCurrent(this.Page).RegisterPostBackControl(lb);
        }

    }
    protected void ContactsGridView_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if (e.CommandName == "PreviewContact")
        {

            _presenter.OnPreviewContactClicked((string)e.CommandArgument);
        }
    }

Related Topic

Refresh a control on the master page after postback