Multiple independent datasets

rbuser

I've been trying to avoid using master-detail relationship. I've
tentatively put what would have been child-table records into separate files
for portability, where the number of such files varies. Is it possible to
include each of those files in report-subreports where after the first file
is traversed the next file is assigned to the pipeline, traversed, and on
through the last file? From your developer's guide page 41, a known number
of independent datasets (no master or linkage) can be placed each in its own
subreport as 'chapters' at design time. When the number of datasets and
subreports is unknown at design time it sounds like I would need to instead
create the report and subreports in code, I suppose loading the subreports
and assigning datasets once the number of such has been determined at run
time? Not something that can be done at design time?

Thanks in advance.

Charles Wood

nicocizik

Hi Charles,

ReportBuilder does not contain a feature that will dynamically create
subreports depending on how many dataset you have, this must be done at run
time. It should not be that difficult however. Take a look at the
following article on creating subreports in code, then you may want to take
a look inside the TechTips newsgroups under the Code Based topic for more
useful articles on creating report object in code. Let me know if you have
any questions along the way.

-------------------------------------------------
TECH TIP: Creating a SubReport in Code
-------------------------------------------------

A subreport is comprised of two objects:

1. SubReport control
The subreport control is added to a band of the
'parent' report. It has properties such as
ShiftRelativeTo, PrintBehavior, etc.
In the Report Designer, the subreport is drawn
as a rectangle.


2. ChildReport
The child report is a descendant of CustomReport and has
most of the same properties as a standard Report.
The child report has a separate layout workspace in the report
designer that is accessible by selecting the tabs at the bottom
of the designer.




When dynamically creating a subreport in code you need to create the
subreport and the underlying child report. The subreport.Report property can
then be used to access the child report.

This is demonstrated in the following example:




var
lSubReport: TppSubReport;
lReport: TppChildReport;
lLabel: TppLabel;
lDBText: TppDBText;


begin

lSubReport := TppSubReport.Create(Self);

{add to the main report's detail band}
lSubReport.Band := ppReport1.DetailBand;

{create the child report (parameters: main report) }
lSubReport.CreateReport(ppReport1);

lReport := TppChildReport(lSubReport.Report);

{assign a datapipeline}
lReport.DataPipeline := plCustomers;

{create the default set of bands}
lReport.CreateDefaultBands;

lLabel := TppLabel.Create(Self);
lLabel.Band := lReport.TitleBand;
lLabel.Caption := 'Customers';

lLabel.Font.Name := 'Times New Roman';
lLabel.Font.Size := 24;

lDBText := TppDBText.Create(Self);
lDBText.Band := lReport.DetailBand;
lDBText.DataPipeline := plCustomers;
lDBText.DataField := 'CustNo';

lDBText.Color := clYellow;
lDBText.Font.Name := 'Times New Roman';
lDBText.Font.Size := 12;



end;


--

rbuser

Thanks for your quick reply. I see I can add a varying number of pbSection
subreports in code, with dbCalc in the summary band. I like it. Adding a
dbCalc to the parent report yeilds zero as the grand total, and I wonder if
I am supposed to be using a variable component there instead as an
accumulator? I assume the dbCalc default type is SUM?

Thanks again.

Charles

nicocizik

Hi Charles,

Yes, when making calculations across subreports into the main report, you
will need to use variables instead of DBCalc components. All you need to do
is place a TppVariable inside the detail band of the subreport and inside
its OnCalc event, update the value property of any other variables in your
report (i.e. in the summary band of the main report).

--
Regards,

Nico Cizik
Digital Metaphors
http://www.digital-metaphors.com

rbuser

Hi Nico,

Before proceeding in code, in the designer I am playing with a report that
contains two pbsection subreports. I can't get the report's summary band
tppvariable to update in other than dtString, and the component doesn't seem
to get its value property at the right time.

I put a TppVariable inside the detail band of the second subreport. And I
put a TppVariable in the summary band of the report and use the OnCalc event
of the second subreport TppVariable to update the value of the summary band
report TppVariable. Note these are currency fields in the table itself.

The report's summary band variable is only non-zero when its data type is
dtSring. That is the case regardless if I use the fields asstring property
in the subreport variables calc event, or just take the subreport
summarybands dbcalc.value, which is a currency field in the table and dbcalc
component. dtCurrency for the report summary band variable always gives a
zero result.

And the report summary band tppvariable's value isn't produced at all if in
the report previewer at run time I use the last page arrow to display the
summary page. The value seems to only be calculated if I step through the
report one page at a time to get to the summary page of the report.

I can't quite see what I am doing wrong and would appreciate any
suggestions. Eventually I'ld like both subreport1 and subreport2's
tppVariable components to update the report summary band tppvariable to
produce a grand total for both subreports.

Charles

nicocizik

Hi Charles,

Sorry, I'm having trouble visualizing what is happening that could be
causing this behavior. If possible, please send a small example of this
issue to support@digital-metaphors.com in .zip format and I'll take a look
at it for you.

--
Regards,

Nico Cizik
Digital Metaphors
http://www.digital-metaphors.com

rbuser

I got it working and wanted to thank you again for your help.

Charles