Different report when datasource has no data

rbuser

Hello NG,

I want to load a different report when the datasource of the report has no
data. So I tried to load a certain template in the "OnNoData" event of the
report. I tried this with an empty datasource but the event doesn't get
fired.
Is there anything I can do about it?

Thanks,

Alex

rbuser

nicocizik

Hi Alexander,

If you are loading templates, you may be loosing your event handlers. In my
testing, the OnNoData event seems to fire correctly. See the following
article for information on loosing event handlers when using report
templates.

--------------------------------------------
Article: Troubleshooting Lost Event Handlers
--------------------------------------------

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:

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

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);


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.


--

rbuser

Hi Nico,

nicocizik

Hi Alex,

Sorry, I should have picked this up from your original post. It is not
possible to load a template after Report.Print has already been called. To
work around this issue, you will need to either check for no data before the
report is executed or use the NoDataBehaviors property of the TppReport
object.

--

rbuser

Hi Nico,

nicocizik

Hi Alex,

Yes, this is similar to how ReportBuilder checks for no data.

if (DataPipeline <> nil) and ((ppdaNoRecords in DataPipeline.State) or
(DataPipeline.BOF and DataPipeline.EOF))

Above is the exact code used to fire the OnNoData event in ReportBuilder.

--

rbuser

Hello Nico,

Nico Cizik (Digital Metaphors)


Thanks for your help. I'll try to solve my problem this way.

Alex