app/models/branch.rb
class Branch < ActiveRecord::Base
belongs_to :agency
has_one :address, as: :location, dependent: :destroy
accepts_nested_attributes_for :address
has_many :agency_people, dependent: :nullify
validates_presence_of :code
validates_length_of :code, maximum: 8
validates_uniqueness_of :code, scope: :agency_id
validates_presence_of :agency_id
end