rails--rails/activerecord/test/models/company_in_module.rb

require "active_support/core_ext/object/with_options"

module MyApplication
  module Business
    class Company < ActiveRecord::Base
    end

    class Firm < Company
      has_many :clients, -> { order("id") }, dependent: :destroy
      has_many :clients_sorted_desc, -> { order("id DESC") }, class_name: "Client"
      has_many :clients_of_firm, -> { order "id" }, foreign_key: "client_of", class_name: "Client"
      has_many :clients_like_ms, -> { where("name = 'Microsoft'").order("id") }, class_name: "Client"
      has_one :account, class_name: "MyApplication::Billing::Account", dependent: :destroy
    end

    class Client < Company
      belongs_to :firm, foreign_key: "client_of"
      belongs_to :firm_with_other_name, class_name: "Firm", foreign_key: "client_of"

      class Contact < ActiveRecord::Base; end
    end

    class Developer < ActiveRecord::Base
      has_and_belongs_to_many :projects
      validates_length_of :name, within: (3..20)
    end

    class Project < ActiveRecord::Base
      has_and_belongs_to_many :developers
    end

    module Prefixed
      def self.table_name_prefix
        "prefixed_"
      end

      class Company < ActiveRecord::Base
      end

      class Firm < Company
        self.table_name = "companies"
      end

      module Nested
        class Company < ActiveRecord::Base
        end
      end
    end

    module Suffixed
      def self.table_name_suffix
        "_suffixed"
      end

      class Company < ActiveRecord::Base
      end

      class Firm < Company
        self.table_name = "companies"
      end

      module Nested
        class Company < ActiveRecord::Base
        end
      end
    end
  end

  module Billing
    class Firm < ActiveRecord::Base
      self.table_name = "companies"
    end

    module Nested
      class Firm < ActiveRecord::Base
        self.table_name = "companies"
      end
    end

    class Account < ActiveRecord::Base
      with_options(foreign_key: :firm_id) do |i|
        i.belongs_to :firm, class_name: "MyApplication::Business::Firm"
        i.belongs_to :qualified_billing_firm, class_name: "MyApplication::Billing::Firm"
        i.belongs_to :unqualified_billing_firm, class_name: "Firm"
        i.belongs_to :nested_qualified_billing_firm, class_name: "MyApplication::Billing::Nested::Firm"
        i.belongs_to :nested_unqualified_billing_firm, class_name: "Nested::Firm"
      end

      validate :check_empty_credit_limit

      protected

        def check_empty_credit_limit
          errors.add("credit_card", :blank) if credit_card.blank?
        end
    end
  end
end