Question

I have ViewState disabled on my ASPX page:

<%@ Page Title="Home Page" MasterPageFile="~/Views/Shared/WebForm.master" Language="C#" EnableViewState="False" AutoEventWireup="True" CodeBehind="Dashboard.aspx.cs" Inherits="CableSolve.Web.Dashboard.Dashboard"%>

and I have the following class:

public class DashboardUpdatePanel : UpdatePanel
{
    public DashboardUpdatePanel()
    {
        UpdateMode = UpdatePanelUpdateMode.Conditional;
        CssClass = "maxHeight";
    }

    [Category("Appearance")]
    [Description("The CSS class applied to the UpdatePanel rendering")]
    public string CssClass
    {
        get
        {
            string s = (string)ViewState["CssClass"];
            return s ?? String.Empty;
        }
        set
        {
            ViewState["CssClass"] = value;
        }
    }

    protected override void RenderChildren(HtmlTextWriter writer)
    {
        if (IsInPartialRendering == false)
        {
            string cssClass = CssClass;
            if (cssClass.Length > 0)
            {
                writer.AddAttribute(HtmlTextWriterAttribute.Class, cssClass);
            }
        }
        base.RenderChildren(writer);
    }
}

I see effects on my page if I remove the assignment to the CssClass property. Yet, the setter is assigning the value to ViewState.

How does this work? Surely if ViewState is disabled I would not see any difference whether I had CssClass assigned to or not.

Answer 1

Disabling ViewState means that the ViewState will not be persisted across postbacks.

Within a postback, ViewState will still work.