call.rb

class Call < ActiveRecord::Base

  before_destroy :check_associations
  before_validation :normalize_state
  before_save :normalize_times

  belongs_to :clear_unit, :class_name=>"Member"
  belongs_to :call_dispatcher
  belongs_to :call_category

  has_many :patients, :dependent => :restrict
  has_many :responses, :dependent => :destroy, :order => 'arrival ASC' 
  has_many :recordings, :dependent => :destroy
  has_many :city_responders, :dependent => :destroy
  has_many :members, :through => :responses

  accepts_nested_attributes_for :recordings, :city_responders, :responses, :patients

  validates_inclusion_of :reviewed, :in => [true, false], :allow_blank => true

  validates_associated :patients, :responses, :city_responders, :if => :reviewed

...

city_responder.rb

class CityResponder < ActiveRecord::Base

  before_destroy :check_call_reviewed
  before_save :check_call_reviewed
  before_create :check_call_reviewed

  belongs_to :call

....
  
  validates_presence_of :call

  validates_datetime :arrival, :on_or_after => Proc.new { |city_responder| city_responder.call.time }, :on_or_before => Proc.new { |city_responder| city_responder.call.clear_time }, :if => proc { |city_responder| city_responder.call && city_responder.call.reviewed }

end