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StateBag Class

Manages the view state of ASP.NET server controls, including pages. This class cannot be inherited.


Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)

public sealed class StateBag : IStateManager, 
	IDictionary, ICollection, IEnumerable

The StateBag type exposes the following members.

Public methodStateBag()Initializes a new instance of the StateBag class. This is the default constructor for this class.
Public methodStateBag(Boolean)Initializes a new instance of the StateBag class that allows stored state values to be case-insensitive.

Public propertyCountGets the number of StateItem objects in the StateBag object.
Public propertyItemGets or sets the value of an item stored in the StateBag object.
Public propertyKeysGets a collection of keys representing the items in the StateBag object.
Public propertyValuesGets a collection of the view-state values stored in the StateBag object.

Public methodAddAdds a new StateItem object to the StateBag object. If the item already exists in the StateBag object, this method updates the value of the item.
Public methodClearRemoves all items from the current StateBag object.
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetEnumeratorReturns an enumerator that iterates over all the key/value pairs of the StateItem objects stored in the StateBag object.
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsItemDirtyChecks a StateItem object stored in the StateBag object to evaluate whether it has been modified since the call to Control.TrackViewState.
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodRemoveRemoves the specified key/value pair from the StateBag object.
Public methodSetDirtySets the state of the StateBag object as well as the Dirty property of each of the StateItem objects contained by it.
Public methodSetItemDirtySets the Dirty property for the specified StateItem object in the StateBag object.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)

Public Extension MethodAsParallelEnables parallelization of a query. (Defined by ParallelEnumerable.)
Public Extension MethodAsQueryableConverts an IEnumerable to an IQueryable. (Defined by Queryable.)
Public Extension MethodCast<TResult>Casts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)
Public Extension MethodOfType<TResult>Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)

Explicit interface implemetationPrivate methodICollection.CopyToFor a description of this member, see ICollection.CopyTo.
Explicit interface implemetationPrivate propertyICollection.IsSynchronizedFor a description of this member, see ICollection.IsSynchronized.
Explicit interface implemetationPrivate propertyICollection.SyncRootFor a description of this member, see ICollection.SyncRoot.
Explicit interface implemetationPrivate methodIDictionary.AddFor a description of this member, see IDictionary.Add.
Explicit interface implemetationPrivate methodIDictionary.ContainsFor a description of this member, see IDictionary.Contains.
Explicit interface implemetationPrivate propertyIDictionary.IsFixedSizeFor a description of this member, see IDictionary.IsFixedSize.
Explicit interface implemetationPrivate propertyIDictionary.IsReadOnlyFor a description of this member, see IDictionary.IsReadOnly.
Explicit interface implemetationPrivate propertyIDictionary.ItemFor a description of this member, see IDictionary.Item.
Explicit interface implemetationPrivate methodIDictionary.RemoveFor a description of this member, see Remove.
Explicit interface implemetationPrivate methodIEnumerable.GetEnumeratorFor a description of this member, see IEnumerable.GetEnumerator.
Explicit interface implemetationPrivate propertyIStateManager.IsTrackingViewStateGets a value indicating whether state changes are being tracked.
Explicit interface implemetationPrivate methodIStateManager.LoadViewStateRestores the previously saved view state of the StateBag object.
Explicit interface implemetationPrivate methodIStateManager.SaveViewStateSaves the changes to the StateBag object since the time the page was posted back to the server.
Explicit interface implemetationPrivate methodIStateManager.TrackViewStateCauses the StateBag object to track changes to its state so that it can be persisted across requests.

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.
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
                object o = ViewState["Text"]; 
                return (o == null)? String.Empty : (string)o;

                ViewState["Text"] = value;

        public int FontSize
                object o = ViewState["FontSize"];
                return (o == null) ? defaultFontSize : (int)o;
                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>");

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.