Export (0) Print
Expand All

StateManagedCollection.CreateKnownType Method

When overridden in a derived class, creates an instance of a class that implements IStateManager. The type of object created is based on the specified member of the collection returned by the GetKnownTypes method.

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

protected virtual Object CreateKnownType (
	int index
)
protected Object CreateKnownType (
	int index
)
protected function CreateKnownType (
	index : int
) : Object
Not applicable.

Parameters

index

The index, from the ordered list of types returned by GetKnownTypes, of the type of IStateManager to create.

Return Value

An instance of a class derived from IStateManager, according to the index provided.

Exception typeCondition

InvalidOperationException

In all cases when not overridden in a derived class.

The CreateKnownType method is called internally by the StateManagedCollection collection in its implementation of the StateManagedCollection.System.Web.UI.IStateManager.LoadViewState method. Derived collections override the CreateKnownType method to return a default instance of the IStateManager type identified by the provided index, which maps to one of the types returned by the GetKnownTypes method.

The following code example demonstrates how a strongly typed StateManagedCollection class implements the CreateKnownType method. The CycleCollection implementation of CreateKnownType returns the default instance of either a Bicycle or Tricycle object, depending on the index passed. 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 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

Community Additions

ADD
Show:
© 2014 Microsoft