Occurs when the value of the FormView.PageIndex property changes before a paging operation.
The System.Web.UI.WebControls.FormView control raises the FormView.PageIndexChanging event when a pager button (a button with its CommandName property set to "Page") within the control is clicked, but before the System.Web.UI.WebControls.FormView control handles the paging operation. This allows you to provide an event-handling method that performs a custom routine, such as canceling the paging operation, whenever this event occurs.
This event is not raised when you programmatically set the FormView.PageIndex property.
Pager buttons are usually located in the pager row of a System.Web.UI.WebControls.FormView control.
A System.Web.UI.WebControls.FormViewPageEventArgs object is passed to the event-handling method, which allows you to determine the index of the page selected by the user and to indicate that the paging operation should be canceled. To determine the index of the page selected by the user, use the FormViewPageEventArgs.NewPageIndex property. To cancel the paging operation, set the System.ComponentModel.CancelEventArgs.Cancel property of the System.Web.UI.WebControls.FormViewPageEventArgs object to true.
For more information about handling events, see Consuming Events.