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rails--rails/activerecord/examples/associations.rb

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require File.dirname(__FILE__) + '/shared_setup'
logger = Logger.new(STDOUT)
# Database setup ---------------
logger.info "\nCreate tables"
[ "DROP TABLE companies", "DROP TABLE people", "DROP TABLE people_companies",
"CREATE TABLE companies (id int(11) auto_increment, client_of int(11), name varchar(255), type varchar(100), PRIMARY KEY (id))",
"CREATE TABLE people (id int(11) auto_increment, name varchar(100), PRIMARY KEY (id))",
"CREATE TABLE people_companies (person_id int(11), company_id int(11), PRIMARY KEY (person_id, company_id))",
].each { |statement|
# Tables doesn't necessarily already exist
begin; ActiveRecord::Base.connection.execute(statement); rescue ActiveRecord::StatementInvalid; end
}
# Class setup ---------------
class Company < ActiveRecord::Base
has_and_belongs_to_many :people, :class_name => "Person", :join_table => "people_companies", :table_name => "people"
end
class Firm < Company
has_many :clients, :foreign_key => "client_of"
def people_with_all_clients
clients.inject([]) { |people, client| people + client.people }
end
end
class Client < Company
belongs_to :firm, :foreign_key => "client_of"
end
class Person < ActiveRecord::Base
has_and_belongs_to_many :companies, :join_table => "people_companies"
def self.table_name() "people" end
end
# Usage ---------------
logger.info "\nCreate fixtures"
Firm.new("name" => "Next Angle").save
Client.new("name" => "37signals", "client_of" => 1).save
Person.new("name" => "David").save
logger.info "\nUsing Finders"
next_angle = Company.find(1)
next_angle = Firm.find(1)
next_angle = Company.find_first "name = 'Next Angle'"
next_angle = Firm.find_by_sql("SELECT * FROM companies WHERE id = 1").first
Firm === next_angle
logger.info "\nUsing has_many association"
next_angle.has_clients?
next_angle.clients_count
all_clients = next_angle.clients
thirty_seven_signals = next_angle.find_in_clients(2)
logger.info "\nUsing belongs_to association"
thirty_seven_signals.has_firm?
thirty_seven_signals.firm?(next_angle)
logger.info "\nUsing has_and_belongs_to_many association"
david = Person.find(1)
david.add_companies(thirty_seven_signals, next_angle)
david.companies.include?(next_angle)
david.companies_count == 2
david.remove_companies(next_angle)
david.companies_count == 1
thirty_seven_signals.people.include?(david)