Question

I have a problem properly understanding map operations

def map1 = [ name: 'John']
def map2 =  [ name: 'Jane']

assert [ name: 'Jane'] == map1 + map2

I would like to get a resulting map like

[[ name: 'Jane'], [ name: 'John']]

Answer 1

When you do:

map1 + map2

it combines the maps, with the right hand map overwriting any keys it has in common with the left hand map..

so:

[ a:1, b:2 ] + [ b:3, c:4 ] == [ a:1, b:3, c:4 ]

What you want is a list of maps. One option is:

[ map1 ] + map2

Which wraps map1 in a list, and then adds map2 to this list

assert [[ name: 'John'], [ name: 'Jane']] == [ map1 ] + map2