Question

I’m trying to initialize a usercontrol that contains a gridview as hidden when a page first loads. When the user clicks a “Search” button on the page then I want to show the gridview that’s within that usercontrol. I’ve tried a bunch of different methods for showing and hiding the user control. I’ve tried placing the usercontrol in a div and then using style=”display: none” to initialize the div as being hidden, and then in the code behind changing the style to ‘block’. I’ve tried using 2 classes with one class having display set to none and the other with display set to block, and then switching between these 2 classes based on user clicking on “Search” button. I’ve tried using a Panel and setting its visibility to true/false, but the panel never shows when I set its visibility to true after the user clicks on the Search button. All methods I’ve tried, except using a panel and its visibility option, give me the following exception:

{InnerText = '((System.Web.UI.HtmlControls.HtmlContainerControl)(divGrid)).InnerText' threw an exception of type 'System.Web.HttpException'}

Here’s the code I’m using that’s causing me this error:

markup:

<div id="divGrid" runat="server">
    <uc1:ContactsGridUserControl ID="ContactsGridUserControl1" runat="server" UpdateMode="Conditional"/>      
</div> 

<asp:Button ID="btnSearch" runat="server" Text="Search" Font-Size="Small" Height="30px" 
                Width="67px" ClientIDMode="Static" onclick="btnSearch_Click"></asp:Button>

code behind:

protected void btnSearch_Click(object sender, EventArgs e)
{
    //string redirect = CommonStrings.editContactPage;
    bool bStatus = false;

    try
    {
        bStatus = validateFields();

        if (bStatus)
        {
            divGrid.Style["display"] = "block";           

        }
        else
        {
            lblError.Text = "Please enter characters for at least one field below";

        }
    }
    catch (Exception ex)
    {
        lblError.Text = "Exception: " + ex.ToString();
    }
}

protected bool validateFields()
{
    try
    {
        if ((txtbxFirstName.Text != null && txtbxFirstName.Text.Length > 0) ||
            (txtbxLastName.Text != null && txtbxLastName.Text.Length > 0) ||
            (txtbxPhoneNum.Text != null && txtbxPhoneNum.Text.Length > 0) ||
            (txtbxCity.Text != null && txtbxCity.Text.Length > 0) ||
            (txtbxZipCode.Text != null && txtbxZipCode.Text.Length > 0) ||
            (txtDate1.Text != null && txtDate1.Text.Length > 0) ||
            (txtDate2.Text != null && txtDate2.Text.Length > 0) ||
            (txtbxCompanyName.Text != null && txtbxCompanyName.Text.Length > 0))
        {
            return true;

        }
        else
        {
            return false;
        }
    }
    catch (Exception ex)
    {
        lblError.Text = "Exception: " + ex.ToString();
        return false;
    }
}

Full Stack Trace: (I right clicked on Call Stack Window within Visual Studio and chose “show external code”. I’m not sure if I did this right to show full stack trace, as opposed to showing what’s on top of the stack by default)

App_Web_gjla55xr.dll!AdvancedSearch.btnSearch_Click(object sender, System.EventArgs e) Line 50 C#
System.Web.dll!System.Web.UI.WebControls.Button.OnClick(System.EventArgs e) + 0x77 bytes
System.Web.dll!System.Web.UI.WebControls.Button.RaisePostBackEvent(string eventArgument) + 0x71 bytes
System.Web.dll!System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(string eventArgument) + 0xb bytes
System.Web.dll!System.Web.UI.Page.RaisePostBackEvent(System.Web.UI.IPostBackEventHandler sourceControl, string eventArgument) + 0xe bytes
System.Web.dll!System.Web.UI.Page.RaisePostBackEvent(System.Collections.Specialized.NameValueCollection postData) + 0x25 bytes
System.Web.dll!System.Web.UI.Page.ProcessRequestMain(bool includeStagesBeforeAsyncPoint, bool includeStagesAfterAsyncPoint) + 0x15bc bytes
System.Web.dll!System.Web.UI.Page.ProcessRequest(bool includeStagesBeforeAsyncPoint, bool includeStagesAfterAsyncPoint) + 0x8d bytes
System.Web.dll!System.Web.UI.Page.ProcessRequest() + 0x4f bytes
System.Web.dll!System.Web.UI.Page.ProcessRequestWithNoAssert(System.Web.HttpContext context) + 0x16 bytes
System.Web.dll!System.Web.UI.Page.ProcessRequest(System.Web.HttpContext context) + 0x32 bytes
App_Web_gjla55xr.dll!ASP.advancedsearch_aspx.ProcessRequest(System.Web.HttpContext context) + 0x33 bytes C#
System.Web.dll!System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() + 0x65 bytes
System.Web.dll!System.Web.HttpApplication.ExecuteStep(System.Web.HttpApplication.IExecutionStep step, ref bool completedSynchronously) + 0x4c bytes
System.Web.dll!System.Web.HttpApplication.ApplicationStepManager.ResumeSteps(System.Exception error) + 0x13e bytes
System.Web.dll!System.Web.HttpApplication.System.Web.IHttpAsyncHandler.BeginProcessRequest(System.Web.HttpContext context, System.AsyncCallback cb, object extraData) + 0xf8 bytes
System.Web.dll!System.Web.HttpRuntime.ProcessRequestInternal(System.Web.HttpWorkerRequest wr) + 0x1a2 bytes
System.Web.dll!System.Web.HttpRuntime.ProcessRequestNoDemand(System.Web.HttpWorkerRequest wr) + 0x7d bytes
System.Web.dll!System.Web.HttpRuntime.ProcessRequest(System.Web.HttpWorkerRequest wr) + 0x47 bytes
WebDev.WebHost40.dll!Microsoft.VisualStudio.WebHost.Request.Process() + 0x17b bytes
WebDev.WebHost40.dll!Microsoft.VisualStudio.WebHost.Host.ProcessRequest(Microsoft.VisualStudio.WebHost.Connection conn) + 0x6c bytes
[Appdomain Transition]
WebDev.WebHost40.dll!Microsoft.VisualStudio.WebHost.Server.OnSocketAccept(object acceptedSocket) + 0x83 bytes
mscorlib.dll!System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(object state) + 0x2d bytes
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool ignoreSyncCtx) + 0xb0 bytes
mscorlib.dll!System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem() + 0x5a bytes
mscorlib.dll!System.Threading.ThreadPoolWorkQueue.Dispatch() + 0x147 bytes
mscorlib.dll!System.Threading._ThreadPoolWaitCallback.PerformWaitCallback() + 0x2d bytes
[Native to Managed Transition]

Edit: I solved the answer to my problem. I needed to surround the user control with an ajax update panel and have a asyncpostbacktrigger wired to the Search button click event. I also surround the usercontrol with another panel and set that panel’s visibility to true/false from code behind.

updated code:

<asp:UpdatePanel ID="UpdatePanel2" runat="server">
    <ContentTemplate>
        <asp:Panel ID="pnlGrid" Visible="false" runat="server">   
            <uc1:ContactsGridUserControl ID="ContactsGridUserControl1" runat="server" UpdateMode="Conditional"/>
        </asp:Panel>
    </ContentTemplate>
    <Triggers>
        <asp:AsyncPostBackTrigger ControlID="btnSearch" EventName="Click" />
    </Triggers>

Answer 1

I believe the base class for all ASP.NET WebForms controls is HtmlControl which has a Visible property. Would this work?:

divGrid.Visible = true;