Control.SaveViewState Method
Assembly: System.Web (in system.web.dll)
'Declaration Protected Overridable Function SaveViewState As Object 'Usage Dim returnValue As Object returnValue = Me.SaveViewState
protected Object SaveViewState ()
protected function SaveViewState () : Object
Not applicable.
Return Value
Returns the server control's current view state. If there is no view state associated with the control, this method returns a null reference (Nothing in Visual Basic).View state is the accumulation of the values of a server control's properties. These values are automatically placed in the server control's ViewState property, which is an instance of the StateBag class. This property's value is then persisted to a string object after the save state stage of the server control life cycle. For more information, see Introduction to the ASP.NET Page Life Cycle.
When view state is saved, this string object is returned to the client as a variable that is stored in an HTML HIDDEN element. When you author a custom server control with a custom view state, the view state can be managed explicitly with the SaveViewState and LoadViewState methods. For more information, see ASP.NET State Management. For information on implementing a custom session-state provider, see Implementing a Session-State Store Provider.
The following example overrides the SaveViewState method in a custom ASP.NET server control. When this method is invoked, it determines whether the control has any child controls and whether the containing Page object is the result of a postback. If both are true, it changes the Text property of a Label Web server control to read Custom Control Has Saved State. It then saves the view state of the control as an array of objects, named allStates.
Protected Overrides Function SaveViewState() As Object ' Change Text Property of Label when this function is invoked. If HasControls() And Page.IsPostBack Then CType(Controls(0), Label).Text = "Custom Control Has Saved State" End If ' Save State as a cumulative array of objects. Dim baseState As Object = MyBase.SaveViewState() Dim _userText As String = UserText Dim _passwordText As String = PasswordText Dim allStates(3) As Object allStates(0) = baseState allStates(1) = _userText allStates(2) = PasswordText Return allStates End Function
protected Object SaveViewState()
{
// Change Text Property of Label when this function is invoked.
if (HasControls() && get_Page().get_IsPostBack()) {
((Label)(get_Controls().get_Item(0))).set_Text(
"Custom Control Has Saved State");
}
// Save State as a cumulative array of objects.
Object baseState = super.SaveViewState();
String userText = get_UserText();
String passwordText = get_PasswordText();
Object allStates[] = new Object[3];
allStates.set_Item(0, baseState);
allStates.set_Item(1, userText);
allStates.set_Item(2, get_PasswordText());
return allStates;
} //SaveViewState