rails_validates_associated_caching_bug_maybe.rb

## app/models/person.rb 

class Person < ActiveRecord::Base
  has_many :pets
end

## app/models/pet.rb 

class Pet < ActiveRecord::Base
  belongs_to :person
end


## GOOD

>> p = Pet.new(:species => 'dog', :name => 'barky')
=> #<Pet id: nil, species: "dog", name: "barky", created_at: nil, updated_at: nil, person_id: nil>
>> p.person = Person.new(:firstname => 'mister', :lastname => 'talky')
=> #<Person id: nil, firstname: "mister", lastname: "talky", created_at: nil, updated_at: nil>
>> p.save!
  Person Create (0.2ms)   INSERT INTO "people" ("created_at", "updated_at", "lastname", "firstname") VALUES('2009-09-10 20:30:35', '2009-09-10 20:30:35', 'talky', 'mister')
  Pet Create (0.1ms)   INSERT INTO "pets" ("name", "created_at", "updated_at", "person_id", "species") VALUES('barky', '2009-09-10 20:30:35', '2009-09-10 20:30:35', 4, 'dog')
=> true
>> p.person.pets
  Pet Load (0.3ms)   SELECT * FROM "pets" WHERE ("pets".person_id = 4) 
=> [#<Pet id: 4, species: "dog", name: "barky", created_at: "2009-09-10 20:30:35", updated_at: "2009-09-10 20:30:35", person_id: "4">]

## Now add validates associated... new app/models/person.rb

class Person < ActiveRecord::Base
  has_many :pets
  validates_associated :pets
end

## BAD

>> p = Pet.new(:species => 'dog', :name => 'barky')
=> #<Pet id: nil, species: "dog", name: "barky", created_at: nil, updated_at: nil, person_id: nil>
>> p.person = Person.new(:firstname => 'mister', :lastname => 'talky')
=> #<Person id: nil, firstname: "mister", lastname: "talky", created_at: nil, updated_at: nil>
>> p.save!
  Person Create (0.3ms)   INSERT INTO "people" ("created_at", "updated_at", "lastname", "firstname") VALUES('2009-09-10 20:35:33', '2009-09-10 20:35:33', 'talky', 'mister')
  Pet Create (0.1ms)   INSERT INTO "pets" ("name", "created_at", "updated_at", "person_id", "species") VALUES('barky', '2009-09-10 20:35:33', '2009-09-10 20:35:33', 5, 'dog')
=> true
>> p.person.pets
=> []