dry_code.rb

class HierarchyProcessor

  attr_reader :input, :user

  def initialize(input, user)
    raise ArgumentError, "user expected User, was #{ user.class }" unless user.is_a?(User)
    @input = JSON.parse(input)
    @user = user
  end

  [:service_groups, :locations, :roles, :employment_types].each do |type|
    define_method(type) do
      class_name = type.to_s.classify.constantize
      class_name.where(id: @input[type.to_s].map{ |s| s['id'] })
    end
  end

end