MongoDB connection from Jaspersoft ‘iReport’

I have created a few DBs (largely copying pp 137 from the excellent ‘7 databases in 7 weeks’) and manually entered a dozen or so rows. The Mongo equivalent of select * from is dbfind()

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CCgQFjAB&url=http%3A%2F%2Fwww.amazon.co.uk%2FSeven-Databases-Weeks-Modern-Movement%2Fdp%2F1934356921&ei=wzGiUIGQO82W0QXwp4HAAg&usg=AFQjCNGDmifztGqAE-XoQzebWHDB3KjYVg

And I’ve managed to install Japsersoft iReport.

So far, so good.

But…When I create a datasource connection from within iReport to MongoDB I am asked for 3 things
1 MongoURI
2 Username
3 Password

The pre-filled default for 1 is ‘mongodb://HOST:27017/DB_NAME’
I assume I substitute DB_NAME for towns (my recently created database) – but this doesn’t work.
I also assume I can leave a username and password as blank?
– As show users (in Mongo shell) returns nothing (and I haven’t yet created any)

So, brick wall. Have raised a JIRA @ MongoDB, hopefully someone can help me out!