How To…Troubleshoot Lost Event Handlers

Question

“How do I troubleshoot lost event handlers?”

Solution

Let’s assume you have created a report in Delphi and assign an event handlers to the OnPreviewFormCreate event of the report. The event is generated by Delphi as:

Sample Delphi code:

procedure TForm1.ppReport1PreviewFormCreate(Sender: TObject);

1	procedure TForm1.ppReport1PreviewFormCreate(Sender: TObject);

You then save the report to an RTM file ‘Report1.RTM.’ The events are stored as references only, and so the RTM contains:

object ppReport1: TppReport
    .
    .
    OnPreviewFormCreate = ppReport1PreviewFormCreate
end

object ppReport1: TppReport

OnPreviewFormCreate = ppReport1PreviewFormCreate

end

You then go on to work on a different report. Saving it with under then name ‘Report2.RTM’. Only this time, before you save the report you change the report component name to: rptOrders. Delphi automatically updates the event declaration for OnPreviewFormCreate event to:

procedure TForm1.rptOrdersPreviewFormCreate(Sender: TObject);

1	procedure TForm1.rptOrdersPreviewFormCreate(Sender: TObject);

You then create two buttons on the form, one to load Report1 and preview, the other to load Report2 and preview. When you run the app and click Report1, you an error. This is because the Report1.RTM file contains a reference to ppReport1PreviewFormCreate, a method which no longer exists (at least with this name) in the form.

One answer is to load all your rtm files into the report component you will be using for loading. Fix any errors, reassign any events that get cleared. This will update your rtms to contain the proper event handler names.