Hi there

I have a usercontrol with a number of properties. These properties are not getting 'remembered' between postbacks. I have tried setting the page's and the control's EnableViewState properties to true, but this doesn't make any difference.

 
Two questions:

1) How do I specify that the user control remembers its properties between postbacks?

2) What is the control's EnableViewState property for?

Thanks

David 

You need to override SaveControlState() and LoadControlState().

Here's an example:

	private string _HeaderText;
	public string HeaderText
	{
		get { return _HeaderText; }
		set
		{
			_HeaderText = value;
			lblHeaderText.Text = _HeaderText;
		}
	}

	protected override object SaveControlState()
	{
		object[] controlState = new object[2];
		controlState[0] = base.SaveControlState();
		controlState[1] = _HeaderText;
		return controlState;
	}

	protected override void LoadControlState(object savedState)
	{
		object[] controlState = (object[])savedState;
		base.LoadControlState(controlState[0]);
		_HeaderText = (string)controlState[1];
	}

Isn't it simpler to just use Properties to store the user control's members in ViewState?

get

{

return (string)(ViewState["HeaderText"] ?? (object)"");

}

set

{

ViewState["HeaderText"] = value;

}

For control properties ControlState is a better location because it cannot be turned off by developers using your control. ViewState can be turned off however, so it should not be used for recording critical control information. So properties that are set in the controls markup, ControlState is a much better place to keep such information.

http://msdn2.microsoft.com/en-us/library/1whwt1k7.aspx