Issue with html element runat="server" visibility status

Question

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:

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.

Accepted Answer

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" %>

I'm Visible!

HTMLElement Current State:

should be

Label Current State:

should be

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;
}

}

Answer

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


    Test

Code behind

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

Share via

Issue with html element runat="server" visibility status

1 additional answer

Your answer