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StateManagedCollection.GetKnownTypes Method

When overridden in a derived class, gets an array of IStateManager types that the StateManagedCollection collection can contain.

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

protected virtual Type[] GetKnownTypes()

Return Value

Type: System.Type[]
An ordered array of Type objects that identify the types of IStateManager objects the collection can contain. The default implementation returns null.

The GetKnownTypes method is called internally by the StateManagedCollection collection in its implementation of the SaveViewState method. Derived collections override the GetKnownTypes method to return an array of Type objects that represent the types the collection can contain.

The following code example demonstrates how a strongly typed StateManagedCollection class implements the GetKnownTypes method. The CycleCollection implementation of GetKnownTypes returns a Type array of known types, including Bicycle and Tricycle types. This code example is part of a larger example provided for the StateManagedCollection class.

////////////////////////////////////////////////////////////// 
// 
// The strongly typed CycleCollection class is a collection 
// that contains Cycle class instances, which implement the 
// IStateManager interface. 
// 
//////////////////////////////////////////////////////////////
[AspNetHostingPermission(SecurityAction.Demand, 
    Level=AspNetHostingPermissionLevel.Minimal)]
public sealed class CycleCollection : StateManagedCollection {

    private static readonly Type[] _typesOfCycles 
        = new Type[] { typeof(Bicycle), typeof(Tricycle) };

    protected override object CreateKnownType(int index) {
        switch(index) {
            case 0:
                return new Bicycle();
            case 1:
                return new Tricycle();                    
            default:
                throw new ArgumentOutOfRangeException("Unknown Type");
        }            
    }

    protected override Type[] GetKnownTypes() {
        return _typesOfCycles;
    }

    protected override void SetDirtyObject(object o) {
        ((Cycle)o).SetDirty();
    }

}

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

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