Issue with html element runat="server" visibility status

Question

Issue with html element runat="server" visibility status

Jason Baginski 106

I was updating an old project with a new feature a customer requested and found a frustrating problem.

In this particular case, there is an html table in my aspx where a table row is set as runat="server" so the visibility state could be controlled in the aspx.cs. Here's a rough concept of it:

<table>
<tr runat="server" id="tr_1"><td></td></tr>
</table>

Here's the issue.

tr_1.Visible=true;
if(!tr_1.Visible)
  DoesntMakeSense(); // should never happen, but does.

On my next postback, tr_1.Visible is true.

Actual server controls like Panel/Label/TextBox/etc when you set the Visible status, checking immediately after gives the status I just set.

Is there some sort of commit function I need to run to make sure ASP.NET gives me the proper status on generic html elements that are runat="server"?

Note, this is a "what do I do to make this work as expected?" not a "what alternatives do I have to doing this" question.

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Answer accepted by question author

Jason Baginski 106

I figured it out. The content was in a panel that wasn't set visible until after the code that set the HtmlElement's visibility. Here's example code replicating what I was experiencing allowing to toggle back and forth between setting the parent panel visibility before or after setting the HtmlElement visibility.

I created a sample page, but for some unknown reason, these forums won't allow me to save the post if I include the aspx lines for the buttons. I've been trying for 40 minutes now.

Here's everything, but you'll have to put your own buttons on the aspx one called b_Visible Text="Visible", the other called b_Hidden with Text="Hide" with the appropriate OnClick events below the CheckBox.

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Test.aspx.cs" Inherits="Test" %>

<!DOCTYPE html>
<html>
<body>
<form id="form1" runat="server">
<asp:Panel runat="server" ID="p_ParentPanel" Visible="false">
<table>
<tr runat="server" id="tr_1">
<td>I'm Visible!</td>
</tr>
</table>
<asp:Label runat="server" ID="l_Test" Text="Label Visible!" />
</asp:Panel>
<hr />
<div>
HTMLElement Current State:
<asp:Label runat="server" ID="l_tr_ReportedState" Text="" />
should be
<asp:Label runat="server" ID="l_tr_ShouldBe" Text="" />
</div>
<hr />
<div>
Label Current State:
<asp:Label runat="server" ID="l_l_ReportedState" Text="" />
should be
<asp:Label runat="server" ID="l_l_ShouldBe" Text="" />
</div>
<hr />
<asp:CheckBox ID="cb_PreSetPanel" runat="server" Text="Set panel visibility first" /><br />

</form>
</body>
</html>

using System;

public partial class Test : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}

protected void b_Visible_Click(object sender, EventArgs e)
{
    HideStuff(true);
}

protected void b_Hidden_Click(object sender, EventArgs e)
{
    HideStuff(false);
}

private void HideStuff(bool visible)
{
    if(cb_PreSetPanel.Checked)
        p_ParentPanel.Visible = visible; // If I make the parent panel visible first, it gives expected results
    tr_1.Visible = visible;
    l_Test.Visible = visible;
    l_tr_ShouldBe.Text = visible.ToString();
    l_tr_ReportedState.Text = tr_1.Visible.ToString();
    l_l_ShouldBe.Text = visible.ToString();
    l_l_ReportedState.Text = l_Test.Visible.ToString();
    if(!cb_PreSetPanel.Checked)
        p_ParentPanel.Visible = visible;  // Order of operations of parent panel is apparently the culprit

    b_Visible.Enabled = !visible;
    b_Hidden.Enabled = visible;
}

}

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1 additional answer

Your answer

Answer 1

AgaveJoe 31,361

I can't reproduce this issue. I assume there is something else going on with the code that we cannot see.

<tr runat="server" id="tr_1">
    <td>Test</td>
</tr>

Code behind

    protected void Button1_Click(object sender, EventArgs e)
    {
        tr_1.Visible = false;
        Label1.Text = tr_1.Visible.ToString();
    }

Jason Baginski 106 Reputation points

2021-09-24T14:30:32.723+00:00

II want to reply with sample code, but I'm getting:

Access Denied
You don't have permission to access "http://learn.microsoft.com/answers/answers/565322/post.html" on this server.
Reference #18.c90ec617.1632493803.267623b
Jason Baginski 106 Reputation points

2021-09-24T14:59:15.33+00:00

This forum is absolutely horrific. I've tried several times to paste in bits from my full answer reply and when I click Submit, it changes colors and disables and just sits there. Typing this to see if it allows small replies.

Jason Baginski 106

protected void b_Visible_Click(object sender, EventArgs e)
{
HideStuff(true);
}

    protected void b_Hidden_Click(object sender, EventArgs e)
    {
        HideStuff(false);
    }

    private void HideStuff(bool visible)
    {
        if(cb_PreSetPanel.Checked)
            p_ParentPanel.Visible = visible; // If I make the parent panel visible first, it gives expected results
        tr_1.Visible = visible;
        l_Test.Visible = visible;
        l_tr_ShouldBe.Text = visible.ToString();
        l_tr_ReportedState.Text = tr_1.Visible.ToString();
        l_l_ShouldBe.Text = visible.ToString();
        l_l_ReportedState.Text = l_Test.Visible.ToString();
        if(!cb_PreSetPanel.Checked)
            p_ParentPanel.Visible = visible;  // Order of operations of parent panel is apparently the culprit

        b_Visible.Enabled = !visible;
        b_Hidden.Enabled = visible;
    }

Jason Baginski 106 Reputation points

2021-09-24T15:03:53.257+00:00

I can post my aspx.cs content, but not my aspx content. Site is so broken.

Jason Baginski 106

<asp:Panel runat="server" ID="p_ParentPanel" Visible="false">
                <table>
                    <tr runat="server" id="tr_1">
                        <td>I'm Visible!</td>
                    </tr>
                </table>
                <asp:Label runat="server" ID="l_Test" Text="Label Visible!" />
            </asp:Panel>

Jason Baginski 106

<hr />
            <div>
                HTMLElement Current State:
            <asp:Label runat="server" ID="l_tr_ReportedState" Text="" />
                should be
            <asp:Label runat="server" ID="l_tr_ShouldBe" Text="" />
            </div>
            <hr />
            <div>
                Label Current State:
            <asp:Label runat="server" ID="l_l_ReportedState" Text="" />
                should be
            <asp:Label runat="server" ID="l_l_ShouldBe" Text="" />
            </div>

Jason Baginski 106

        <hr />
        <asp:CheckBox ID="cb_PreSetPanel" runat="server" Text="Set panel visibility first" /><br />

Jason Baginski 106 Reputation points

2021-09-24T15:08:06.093+00:00

I have two buttons below that, one called b_Visible Text="Visible", the other called b_Hidden with Text="Hide" with the appropriate OnClick events. This horrific forum will not save a reply if they are included.

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Issue with html element runat="server" visibility status

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