Delphi: Canceling a TDataSet.Post in an OnBeforePost Event

delphi delphi-7 tdataset
Christopher Chase picture Christopher Chase · May 8, 2009 · Viewed 14.4k times · Source

On our main data entry screen, we have an OK/Cancel dialog in the OnBeforePost event.

  • OK lets things take their course
  • Cancel right now does a Dataset.Cancel;

Which does what it's meant to, roll back any changes and puts the dataset into browse mode.

This is fine for most of the clients, but we have been asked if it can be changed to

  • Cancel, Abort the Post and stay in edit mode with the current changes kept.

If they want to cancel, they can use the cancel button.

Looking at the source for procedure TDataSet.Post; it does not look possible to use the event this way.

Dose anyone have any thoughts on a way this could be done?

Follow Up: this is how I have chosen to handle it now

case MessageDlg('Save Changes?', mtWarning, [mbYes, mbNo, mbAbort], 0) of
  mrYes: ;
  mrNo: Dataset.Cancel;
  mrAbort: Abort;
  mrNone: Abort;
end;

Answer

onnodb picture onnodb · May 8, 2009

Calling the method Abort (from the unit System, if I recall correctly) raises a silent EAbort exception, which cancels just the current operation. That should work.

(Btw: this method of cancelling a databaset operation is also described somewhere deep in the help system as the 'normal' way to achieve this --- that's where I got this technique from originally).

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