RB effect DataChange event of DataSource

rbuser

I don't understand with running a report would trigger the DataChange event
on my DataSource. To get around the problem, I have set the following
properties in my DBPipeLine.

MoveBy := 0;
RangeBegin := rbCurrentRecord;
RangeEnd := rbCurrentRecord;
SkipWhenNoRecords := False;

This still triggers the DataChange event on my DataSource. What am I doing
wrong?

Kevin

digitalmetaphors

From the Delphi help on this event:

Methods that can trigger this event include the Next or Prior methods for
the dataset. Data-aware controls notify a data source of a data change when:

Scrolling to a new record.
Modifications to a field's data.


Cheers,

Jim Bennett
Digital Metaphors

rbuser

Ok, I understand that, but I am only printing 1 row from my dataset. The
table that the report is based is filtered to 1 row of data. Why would RB
issue a first or prior method, especially when I set the RangeBegin and
RangeEnd of the DBPipeline to rbCurrentRecord?

Kevin

rbuser

Just for the record, I was able to get around this by using the StateChange
event instead. I still would like to know why RB is moving the record
pointer when I have indicated to use the current record only.

Kevin

digitalmetaphors

I don't believe the code is optimized for this case. Next is called until
EOF is true on the pipeline.


Cheers,

Jim Bennett
Digital Metaphors

rbuser

That seems like a common bug. The code should be "while not eof do Next"
instead of "repeat Next until eof".

Richard

digitalmetaphors

When the pipeline opens, it moves the dataset to the first record, causing
the datachange event to fire. To see what is happening, you can change your
library path to point to ..\RBuilder\Source and put a breakpoint at the
beginning of your OnDataChange event handler and then put a breakpoint in
ppEngine.pas in the procedure TppEngine.OpenDataPipelines; on the line
which calls FMasterDataPipeline.First and this is the start of the sequence
leading up to the OnDataChange event.



Cheers,

Jim Bennett
Digital Metaphors


"Richard Biffl" wrote