Custom Expressions/Functions

[edeards]

Hi all,

I'm writing a report generation system which builds pdf fragments from assorted datasources and tacks them together to form a big report. As a consequence I'm trying to generalise all my input fields in such a way that for all these jasper report fragments, I provide the same fields in a JRMapCollectionDataSource.

This works fine so far.

However I have a subreport in one report which needs to sum a column and place a total in the footer band. Again, this would be simple - if my fields were Integers rather than Strings!

I do have a mechanism in my own code to change this - however it's something I'm prefering use as infrequently as possible, as it means I'm breaking away from my generalised interface.

I cannot see any function within the iReport expression builder that allows me parse Integers from the String fields. I'm hoping there is some mechanism by which I can write my own function/expression handling code and plug it into the jasper engine. Does such a mechanism exist?

Thanks for any advice!

[lucianc]

You can parse Strings into Integers via the standard Java method Integer.valueOf(String) (if the number format matches the format that this method expects).

If you want to use your own parsing method, you can do so directly by calling the method in the report expression (i.e. com.me.MyUtils.parseIntegerString($F{field})).

HTH,

Lucian

[edeards]

Ah thanks Lucian.

The fact that expressions in JasperReports are straight java had entirely escaped me. That makes my life far easier.

Thanks!