Scan a dataset

rbuser

Hello DM-team!

Is there a way to loop (while not eof) through a dataset in RAP?

I need to dynamically create a lot of Labels and place them on a grid in a
single-page
report. The Labels will be placed in the grid where Label.left is calculated
from a DateTime value
in the dataset and the Label.Top is calculated from the day of a week.

Best regards,
Terje

nicocizik

Hi Terje,

Two options...

1. Create a pass thru function that traverses your dataset directly and
returns the proper value to the RAP program. For an example of creating a
pass thru function, please see the developer's guide located in the
\RBuilder\Developer's Guilde\... directory.

2. Extend the existing RTTI class for the TppDataPipeline and use the Next
method to traverse a datapipeline connected to your dataset from RAP. See
the article below on adding additional support to existing RTTI classes.

--------------------------------------------------
Article: Adding Support to Existing RTTI Classes
---------------------------------------------------

"I notice that TppDataPipeline (or some other class)
has a Next method (or some other member),
but the RAP compiler doesn't seem to recognize that
method, are you going to add support for that?"

There are a number of class members which have not been
added to RAP via the RTTI classes. We have tried to add
support for the most commonly used members. (Keep in
mind that all published properties are supported
automatically, public methods and properties require
a bit of coding to make visible in RAP).

The answer to your question is that, yes, we could
add support for a given member in the next release,
but you can do it yourself more quickly and it is
not very difficult.

Using the RTTI tutorial located in the RAP help file,
you can familiarize yourself with the process. Following
that, you can descend your own RTTI class to add the
support for the member you are lacking.
Take, for instance, the TppDataPipeline that is missing the
Next method. You will find TraTppDataPipelineRTTI in
the ppDB unit. You can descend from TraTppDataPipelineRTTI
in a new unit as
TmyTppDataPipelineRTTI = class(TraTppDataPipelineRTTI).

Add your support to the new class (see the tutorials
for information) and then add the following in
your Initialization/Finalization sections:

Initialization
raUnregisterRTTI(TraTppDataPipelineRTTI):
raRegisterRTTI(TmyTppDataPipelineRTTI);
Finalization
raUnregisterRTTI(TmyTppDataPipelineRTTI);
raRegisterRTTI(TraTppDataPipelineRTTI);

When you add this unit to your projects, your new, improved
RTTI class will replace the old class, thus providing
your new support without having to alter the source
code in any way.


--
Regards,

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