Manages the view state of ASP.NET server controls, including pages. This class cannot be inherited.
(in System.Web.dll)
Visual Basic (Declaration)
<AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class StateBag _
Implements IStateManager, IDictionary, ICollection, IEnumerable
[AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
public sealed class StateBag : IStateManager,
IDictionary, ICollection, IEnumerable
[AspNetHostingPermissionAttribute(SecurityAction::LinkDemand, Level = AspNetHostingPermissionLevel::Minimal)]
public ref class StateBag sealed : IStateManager,
IDictionary, ICollection, IEnumerable
public final class StateBag implements IStateManager, IDictionary, ICollection, IEnumerable
View state for a page or control is the cumulative property values, or view, of that page or control. You can access this class through the Control..::.ViewState property. Controls can also store essential state information in control state, but that information is not stored as a StateBag object.
This class is the primary storage mechanism for all HTML and Web server controls. It stores attribute/value pairs as strings associated with the control. It tracks changes to these attributes only after the OnInit method is executed for a page request, and saves the changes to the page's or control's view state.
This class implements a dictionary, and you can add items to it or remove items from it as you would any dictionary object. For more information about data collections, such as dictionaries, see Collections and Data Structures.
The following code example demonstrates a composite Label control that has Text and FontSize properties. These properties are saved to and retrieved from view state when the Control..::.Render method is called on the control.
' This control renders values stored in view state for Text and FontSize properties.
Imports System
Imports System.Web
Imports System.Web.UI
Namespace ViewStateControlSamples
Public Class CustomLabel : Inherits Control
Private Const defaultFontSize As Integer = 3
' Add property values to view state with set;
' retrieve them from view state with get.
Public Property [Text]() As String
Get
Dim o As Object = ViewState("Text")
If (IsNothing(o)) Then
Return String.Empty
Else
Return CStr(o)
End If
End Get
Set(ByVal value As String)
ViewState("Text") = value
End Set
End Property
Public Property FontSize() As Integer
Get
Dim o As Object = ViewState("FontSize")
If (IsNothing(o)) Then
Return defaultFontSize
Else
Return CInt(ViewState("FontSize"))
End If
End Get
Set(ByVal value As Integer)
ViewState("FontSize") = value
End Set
End Property
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Protected Overrides Sub Render(ByVal Output As HtmlTextWriter)
Output.Write("<font size=" & Me.FontSize & ">" & Me.Text & "</font>")
End Sub
End Class
End Namespace
// This control renders values stored in view state for Text and FontSize properties.
using System;
using System.Web;
using System.Web.UI;
namespace ViewStateControlSamples
{
public class CustomLabel : Control
{
private const int defaultFontSize = 3;
// Add property values to view state with set;
// retrieve them from view state with get.
public String Text
{
get
{
object o = ViewState["Text"];
return (o == null)? String.Empty : (string)o;
}
set
{
ViewState["Text"] = value;
}
}
public int FontSize
{
get
{
object o = ViewState["FontSize"];
return (o == null) ? defaultFontSize : (int)o;
}
set
{
ViewState["FontSize"] = value;
}
}
[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
protected override void Render(HtmlTextWriter output)
{
output.Write("<font size=" + this.FontSize.ToString() + ">" + this.Text + "</font>");
}
}
}
// This control renders values stored in view state for Text and FontSize properties.
import System
import System.Web
import System.Web.UI
package ViewStateControlSamples {
public class Label extends Control {
// Add property values to view state with set;
// retrieve them from view state with get.
public function get Text() : String
{
return String(ViewState["Text"]);
}
public function set Text(value : String)
{
ViewState["Text"] = value;
}
public function get FontSize() : int
{
return int(ViewState["FontSize"]);
}
public function set FontSize(value : int)
{
ViewState["FontSize"] = value;
}
protected override function Render(output : HtmlTextWriter) {
output.Write("<font size=" + this.FontSize + ">" + this.Text + "</font>");
}
}
}
System..::.Object
System.Web.UI..::.StateBag
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
.NET Framework
Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
Reference
Other Resources