Query with aggregate on custom mapping returning wrong type

Question

I've got a JDOQL query that returns the sum of a single column, where that
column is custom-mapped, but the result I get back is losing precision.
I create the JDOQL query as normal and set the result to the aggregate
expression:
KodoQuery query = (KodoQuery) pm.newQuery(candidateClass, filter);
query.setResult("sum(amount)");
I can also setUnique for good measure as I am expecting just 1 row back:
query.setUnique(true);
The query returns an Integer, but my amount column is a decimal with 5
digits after the decimal point. If I ask for a Double or BigDecimal as the
resultClass, it does return an object of that type, but loses all
precision after the decimal point:
query.setResultClass(BigDecimal.class);
The amount field in my candidate class is of the class Money, a class that
encapsulates a currency and a BigDecimal amount. See
http://www.martinfowler.com/ap2/quantity.html
It is mapped as a custom money mapping to an amount and currency column,
based on the custom mapping in the Kodo examples. I have tried mapping the
amount as a BigDecimal value, and querying the sum of this works. So the
problem seems to be the aggregate query on my custom mapping. Do I need to
write some code for my custom mapping to be able to handle aggregates?
Thanks,
Alex

Answer 1

Can you post your custom mapping?
Also, does casting the value have any effect?
q.setResult ("sum((BigDecimal) amount)");