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Control.TrackViewState Method

Causes tracking of view-state changes to the server control so they can be stored in the server control's StateBag object. This object is accessible through the Control.ViewState property.

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

protected virtual void TrackViewState()

This method is called automatically at the end of the Init event in the server control's lifecycle.

Invoke this method when you develop templated data-bound controls. This method alerts ASP.NET to monitor changes to a server control's view state, which is required when you override the Control.DataBind method.

The following example overrides the DataBind method in a custom ASP.NET server control. It begins by calling the base OnDataBinding method and then uses the Clear method to delete all the child controls and the ClearChildViewState method to delete any saved view-state settings for those child controls. Finally, the ChildControlsCreated property is set to true. The control then uses the IsTrackingViewState property to determine whether view-state change tracking is enabled for the control. If it is not enabled, the TrackViewState method is called.

public override void DataBind() 
{
   base.OnDataBinding(EventArgs.Empty);
   // Reset the control's state.
   Controls.Clear();
   // Check for HasChildViewState to avoid unnecessary calls to ClearChildViewState. 
   if (HasChildViewState)
      ClearChildViewState();
   ChildControlsCreated = true;
   if (!IsTrackingViewState)
      TrackViewState();
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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