Using ReportBuilder with DB transactions

rbuser

I have a program which has a couple of transaction controlled routines that
update figures and status fields on the database server. During these
routines there are also reports that need to be printed, and in the case of
a rollback on the database server, the reports are useless and needs to be
thrown away. Are there any easy ways of holding these reports and realease
them on commit?

I'm using ReportBuilder Enterprise Edition v 6.03.

digitalmetaphors

Where are these reports being printed to: archives, dbarchives, printer? If
the report is printed to an archive it is trivial to simply remove the
archive. Such a solution would be sufficient under a light load of
transactions. A heavy transaction load would, however, create a lot of IO
traffic on the server. Another possibility, which can also be used if the
report goes directly into the printer queue is to print the report to a
device and cache the pages in the publisher. In the case of a rollback,
simply reset the publisher to release the report. In the case of a commit,
loop through the cached pages of the publisher and send them to the
appropriate destination device. For example:

When the transaction occurs, print the report:

...
ppReport1.CachePages := True;
ppReport1.PrintToDevices;
...

When the transaction is commited, send it to the printer:

...
lPDevice := TppPrinterDevice.Create(nil);
lPDevice.StartJob;

for liIndex := 0 to ppReport1.Publisher.PageCount - 1 do
begin
lPDevice.Printer.PrinterSetup :=
ppReport1.Publisher.Pages[liIndex].PrinterSetup;
lPDevice.ReceivePage(ppReport1.Publisher.Pages[liIndex]);
end;

lPDevice.EndJob;
...

You can also substitute TppArchiveDevice for TppPrinerDevice.

--
Cheers,

Alexander Kramnik
Digital Metaphors

rbuser

Thanks for responding so quickly.
Alle reports are being printed BOTH to an archive AND to a printer. I also
need to generate up to 200 individual reports before the DataBase.Commit is
called. So maybe the best solution is to store all reports through a
dbarchive and loop the dbarchive after commit? I tried the CachePages
aproach that you suggested, and it seemed to work ok if one report at a time
is being generated and sent. If, however, the same TppReport is being used
to generate several reports before sending the cached pages to the printer,
it seems like only the last report is being printed. Is this correct or
have I done something wrong?
I do not have much experience with using dbarchives. Are there any
resources where I can learn how to use them?

Yours,
Trond Leikvoll

"Alexander Kramnik (Digital Metaphors)" wrote

digitalmetaphors

That is the correct behavior since printing a new report will overwrite the
pages cached by the last report. One approach is to grab the page objects
and store them in your own TList, and maybe keep another list around so you
can bookmark where in the page list each report begins. After calling
PrintToDevices on the report you would loop through the pages in the
publisher and store them, i.e.

var
lPage: TppPage;
liIndex: Integer;
begin
...
for liIndex := 0 to ppReport1.Publisher.PageCount - 1 do
begin
lPage := TppPage.Create(nil);
lPage.Assign(ppReport1.Publisher.Pages[liIndex];
FPages.Add(lPage);
end;
...

Then at a later time you can loop through the pages in that list and send
them to a PrinterDevice and the ArchiveDevice as desired. Follow the link
below for an example of using DBArchive which will hopefully help you get
you on the right track.

http://www.digital-metaphors.com/tips/DBArchiveReader.zip

--
Cheers,

Alexander Kramnik
Digital Metaphors

rbuser

This works perfect. However; I would like to create all the reports as
DBArchive records directly (not files or printers), and then loop the
DBArchive after commit to perform the actual print. Is there an easy way of
doing this directly (i.e. stream the report directly to a TMemoryStream or
something) instead of TFileStream ?

"Alexander Kramnik (Digital Metaphors)" wrote

digitalmetaphors

There is no DBArchiveDevice, we will look into creating this device in a
future release so that you can directly stream a report archive to the
database without having an intermediate file. You can stream a report
archive to a BLOB field with this technique:
http://www.digital-metaphors.com/tips/ArchiveToStream.zip


Cheers,

Jim Bennett
Digital Metaphors