How do I clear and replace a collection in a one-to-many relationship in Grails/Groovy

Question

This question is in two parts, first part is about clearing a list and second part is about assigning an owner to an object.

I have a one-to-many relationship between tw

Answer 1

For #1 you can clear the collection (it's a Set by default):

activePerson.locations.clear()

For #2 use addToLocations:

activePerson.addToLocations(location)

and when you save the person the location<->person relationship will be updated.