Asp.net Client Side State Management-Control State

    Sometimes you need to store control-state data in order for a control to work properly. For example, if you have written a custom control that has different tabs that show different information, in order for that control to work as expected, the control needs to know which tab is selected between round trips.

    The View State property can be used for this purpose, but view state can be turned off at a page level by developers, effectively breaking your control. To solve this, the ASP.NET page framework exposes a feature in ASP.NET called control state.

   The Control State property allows you to persist property information that is specific to a control and cannot be turned off like the View State property.

Control state implementation:

      First, override the OnInit method of the control and add the call for the Page.RegisterRequiresControlState method with the instance of the control to register. Then, override the  LoadControlState and SaveControlState in order to save the required state information.

public class ControlStateWebControl : Control

{

   #region Members 

      private string _strStateToSave;

  #endregion

  #region Methods

  protected override void OnInit(EventArgs e)

   {

     Page.RegisterRequiresControlState(this);

     base.OnInit(e);
    }

   protected override object SaveControlState()

   {

    return _strStateToSave;

   }
  protected override void LoadControlState(object state)

  {

     if (state != null)

     {

       strStateToSave = state.ToString();

     }

  }

#endregion

 }

You need to remember only one thing – the control state takes away the choice to disable View State. You should only use it whenever you have to keep state information that without it your control won’t work.