Occurs before an application posts changes for the active record to the database or cache.
property BeforePost: TDataSetNotifyEvent;
Write a BeforePost event handler to take specific action before an application posts
dataset changes to the database. BeforePost is triggered when an application calls the
Post method. Post checks to make
sure all required fields are present, then calls BeforePost before posting the record.
An application might use BeforePost to perform validity checks on data changes before
posting them to the database. If it encountered a validity problem, it could call Abort to cancel
the Post operation.