Debugging BIRT Javascript

[Paul Bappoo]

I was creating a report in order to answer a query that had been
raised by a reader of BIRT for Beginners where they needed to use the
List Box parameter within a report. In order to do this with BIRT I
needed to use some Javascript in the beforeOpen event of my data set
and I had a problem with the creation of this script. So I needed to
find a way to examine the values of variables while the script was
running to see what I was dealing with and where my error was coming
from.

There are ways to switch on logging from BIRT and dropping values out
to a log file, which you can examine after an execution, but this is a
little long winded for quickly creating and debugging snippets of Java
code, so I wanted to find a faster, more immediate way to interrogate
my script variables.

Looking around on the web I came across a method that involves running
BIRT in the console mode, which means that you get all output from
your script generated immediately to a console window.

This is great because it means that you can tweak your script and
learn the results immediately, making debugging a quick and efficient
process.

CONSOLE MODE

First we need to launch BIRT in Console mode, so we get to see our
console window alongside the main BIRT IDE.

Do this by running eclipsec.exe, using a command line like this:

"C:\BIRT 251\eclipsec.exe"

Notice that this is different to the usual eclipse.exe with the
addition of the letter “c”, you will notice that BIRT runs in the
normal way, but with a console available too.

THE BASIC REPORT

To demonstrate the use of the console window for output, create a
simple listing report based on any data set that you choose. For my
example I used the ClassicModels customer table and just listed out
all customers.

ACCESSING THE SCRIPT AREA

Next I created a small piece of script in my report, which simply
setup a for loop, to display a counter. There are various areas within
a BIRT report where you can access the scripting area so for our
example I am going to use the data set.

Select your data set and then click on the script tab at the bottom of
the main layout window, ensure that beforeOpen is the selected script
event.

GENERATING OUTPUT TO THE CONSOLE

Enter this script:

for(int i=1; i<11; i++)
{
Packages.java.lang.System.out.println ("Count is: " + i);
}

This would seem to set up a for loop to increment a variable (i) value
and stop when the value of i reaches 11, then print the value of i to
the console window. But it contains an error.

Run your report and you should see the console window displays the
error message:

The full version of this report, including screen shots and source
code, in full colour pdf is available for free download at
http://www.BIRTReporting.com


To fix the script, change the reserved word “int” on line 1 to declare
the i variable correctly, as follows:

for(var i=1; i<11; i++)
{
Packages.java.lang.System.out.println ("Count is: " + i);
}

The important thing to notice here, is that we have returned the value
of the variable i to the console window while the report was running.
This can of course be applied to any variable that you have in your
script and should help with your scripting and debugging efforts.

MORE INFORMATION

BIRT for Beginners, written by Paul Bappoo, the founder of the BIRT
User Group UK presents an overview of the open source BIRT tools and
the commercial enhancements available from Actuate, including...
• Eclipse BIRT Designer
• Actuate BIRT Designer
• iServer Express
• Interactive BIRT viewer
• Actuate BIRT Studio
• BIRT Spreadsheet Designer
With walkthrough tutorials of the main features, including
screenshots, from installation through data selection to formatting
reports and fully graphical Flash charting this book will have you
creating your own reports from scratch in only a couple of hours.
If you are too busy to spend days learning software and want tangible
results fast then BIRT For Beginners is for you.
When you buy the book you will automatically get access to the readers
section of this web site which includes BIRT report request forms that
you can distribute to your end users, extra chapters in PDF format and
an ever growing library of reports, tutorials, reviews, tips & tricks.

Buy the book and get free membership of BIRT Reporting and the BIRT
User Group UK at:
http://www.BIRTReporting.com
Please feel free to share this address with your colleagues and
inspire them to use BIRT to create great looking reports.
I look forward to your feedback so please feel free to send me an
email and let me know how you get on with BIRT, provide feedback on
this guide, share your tips and tricks, or request help for specific
problems. I can’t guarantee to personally solve everyone’s problems
but there are some great BIRT related forums out there and you can
find a growing list of links and resources on my site.

HOW TO CONTACT THE AUTHOR

Email: Pa...@BirtReporting.com

Web Site: http://www.BirtReporting.com

Paul Bappoo is the author of BIRT for Beginners (which is available in
paperback from BIRTReporting.com, Amazon and Barnes and Noble amongst
others) and has been an international technical software consultant
and involved with computers for over 30 years. Paul has an interest in
BIRT reporting, enterprise application integration, automated software
testing, computer based training and enterprise system implementation.
Paul runs the BIRT User Group UK and is a member of the BIRT-Exchange
Advisory Council. He would be delighted to hear from you with your
tips, tricks and stories about your usage of BIRT. If you have a
question, a need for training or consulting or great tip to share with
the community then drop him a line.

The full version of this report, including screen shots and source
code, in full colour pdf is available for free download at
http://www.BIRTReporting.com