Multiple inserts on a through association.

class Trunk < ActiveRecord::Base

  has_many :call_type_trunks   has_many :call_types, :through => :call_type_trunks

end

class CallType < ActiveRecord::Base

  has_many :call_type_trunks   has_many :trunks, :through => :call_type_trunks

end

class CallTypeTrunk < ActiveRecord::Base   belongs_to :call_type   belongs_to :trunk end

The associaton class has a column named price. Each association trunk/call_type will have a differente price.

When i choose to add a trunk. I want to list all call_types to allow the users to add/edit both: the call_type ( associate or remove ) call_types to this trunk... and to edit price for each association that exist.

How can I achieve this behavior?