DMZ 1.7.1 (DataMapper OverZealous Edition)

[eluser]OverZealous[/eluser]
@backstack
You always need to first load the object before saving it. It also provides a nice safety net of verifying the input.

Alternatively, look at the update method if you are simply updating one or more objects and don't need validation or verification.

For the last question, you'll just need to be creative. :-)