|
TMemDataSet.OnUpdateError Event |
|
|
|
TMemDataSet.OnUpdateError Event |
|
Occurs when an exception is generated while cached updates are applied to a database.
property OnUpdateError: TUpdateErrorEvent;
Write the OnUpdateError event handler to respond to exceptions generated when cached updates are applied to a database.
E is a pointer to an EDatabaseError object from which application can extract an error message and the actual cause of the error condition. The OnUpdateError handler can use this information to determine how to respond to the error condition.
UpdateKind describes the type of update that generated the error.
UpdateAction indicates the action to take when the OnUpdateError handler exits. On entry into the handler, UpdateAction is always set to uaFail. If OnUpdateError can handle or correct the error, set UpdateAction to uaRetry before exiting the error handler.
The error handler can use the TField.OldValue and TField.NewValue properties to evaluate error conditions and set TField.NewValue to a new value to reapply. In this case, set UpdateAction to uaRetry before exiting.
Note: If a call to ApplyUpdates raises an exception and ApplyUpdates is not called within the context of a try...except block, an error message is displayed. If the OnUpdateError handler cannot correct the error condition and leaves UpdateAction set to uaFail, the error message is displayed twice. To prevent redisplay, set UpdateAction to uaAbort in the error handler.