controller.rb

def set_items
    items_params = []
    params['barter'].each do |barter|
      barter['items'].each do |items|
        items_params << Item.new(amount: items['amount'], kind: items['kind'], survivor_id: barter['survivor_id'] )
      end
    end
    @items_to_barter_a = items_params.select { |key, value| key.survivor_id == @survivors[0].id }
    @items_to_barter_b = items_params.select { |key, value| key.survivor_id == @survivors[1].id }
  end


    def set_survivors
      @survivors = params['barter'].map { |survivor| Survivor.find(survivor['survivor_id']) }
    end