Lifecycle To Access Viewstate?

Nov 8, 2010

In building custom controls, I've seen two patterns for using the viewstate. One is to use properties to disguise the viewstate access as persistent data.

public bool AllowStuff
{
get
{
return (ViewState[constKeyAllowStuff] != null) ?
(bool)ViewState[constKeyAllowStuff] : false;
}
set { ViewState[constKeyAllowStuff] = value; }
}

The other is to use private member fields and to override the Load/SaveViewState methods on the control and handle it all explicitly:

protected override object SaveViewState()
{
object[] myViewState = new object[2];
myViewState[0] = base.SaveViewState();
myViewState[1] = _allowStuff;
return myViewState;
}
protected override void LoadViewState(object savedState)
{
object[] stateArray = (object[])savedState;
base.LoadViewState(stateArray[0]);
_allowStuff = (bool)stateArray[1];
}

(I cut out a lot of safety checking for clarity, so just ignore that.) Is there are particular advantage to one method over the other? I can't see how they'd differ much performance wise. Version 1 is lazy, so I guess you save a bit if you don't need that particular value during a pass. Version 1 is also more abstract, hides the details better. Version 2 is clearer about when the data is actually valid and ok to read or modify (between the load and save) because it more clearly works within the ASP.NET lifecycle. Version 2 does tend to require more boilerplate code though (a property, a backing private field, and viewstate handling in two places) as opposed to Version 1 which combines all that into one place.

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