Handles the synchronous event that occurs before an item is changed.
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Available in Sandboxed Solutions: Yes
Available in SharePoint Online
This event can be used in response, for example, to a form edit, a datasheet post, an object model call, or a Web service call.
When you add a new item, only the ItemAdding event is raised. However, in cases where Explorer View is used, both the ItemAdding and this events are raised. In such cases, this event always occurs after the ItemAdding event occurs.
When a Boolean column value in a list is set to true and the ItemUpdating method is called, the AfterProperties property reports -1 as the value instead.