Complex Form Nesting in Rails - How to create the desired hash / array params output

Question

I'm trying to figure out how to properly handle the params hash so as I dont pass params that should be nested multiple times..

Here is a simplified(removed not-needed info like labels etc) of my html.slim code (using simple_form):

= f.simple_fields_for :room do |r|
    - (1..4).each do |room|
      = r.input 'adults',:collection => 1..4,:input_html => {:name => "room[adults][]"}
      = r.input 'children',:collection => 0..2,:input_html => {:name => "room[children][]"}
      - (1..2).each do |child|
        = r.input 'child_age',:input_html => {:name => "children[#{child}][ages][]"}

ok this with inputs of 1 room, 1 adult,1 child of age 5 we get params like this :

"room"=>{"adults"=>["1", "1", "1", "1"], "children"=>["1", "0"]}, "children"=>{"1"=>{"ages"=>["5", ""]}, "2"=>{"ages"=>["", ""]}}

what I actually want to have on params is this:

"room"=>{"adults"=>["1", "1", "1", "1"], "children"=>["1"=>["5",""], "0"=>["",""]] }

anyone got any idea on how to do that?