belongs_to / has_many not behaving as expected in Rails console - ruby-on-rails-3

Question

models:
class Person < ActiveRecord::Base
attr_accessible :email, :first, :last, :uuid, :books
has_many :books
end
class Book < ActiveRecord::Base
belongs_to :person
attr_accessor :blurb, :published, :title, :person
attr_accessible :person
end
I created a Person using the Rails 3.2.8 console like this:
person = Person.create!( {:first => "John", :last => "Doe"} )
and then created a Book
book = Book.create!( {:title => "Ruby for Dummies"} )
I then try to associate them like this:
person.books << book
When I query the person for books, I get an array with the book I created, but when I query the book for the person it belongs to, I get nil. I expected to get the person, given that all information was persisted (I see the SQL commands and I checked the database and the data is correct, i.e. the row in the book table points back to the person id it should.)
What am I missing?
thanks
Edit- Schema:
CREATE TABLE `persons` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`first` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
`last` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
`uuid` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
`email` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
`created_at` DATETIME NOT NULL,
`updated_at` DATETIME NOT NULL,
PRIMARY KEY (`id`)
)
COLLATE='utf8_unicode_ci'
ENGINE=InnoDB
AUTO_INCREMENT=2;
CREATE TABLE `books` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`title` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
`blurb` TEXT NULL COLLATE 'utf8_unicode_ci',
`published` TINYINT(1) NULL DEFAULT NULL,
`person_id` INT(11) NULL DEFAULT NULL,
`created_at` DATETIME NOT NULL,
`updated_at` DATETIME NOT NULL,
PRIMARY KEY (`id`)
)
COLLATE='utf8_unicode_ci'
ENGINE=InnoDB
AUTO_INCREMENT=3;

Answer 1

Assuming your migrations are correct, there is nothing wrong with your code which should produce the following results:
1.9.3p194 :001 > person = Person.create!( {:first => "John", :last => "Doe"} )
(0.1ms) begin transaction
SQL (145.9ms) INSERT INTO "people" ("book_id", "created_at", "email", "first", "last", "updated_at", "uuid") VALUES (?, ?, ?, ?, ?, ?, ?) [["book_id", nil], ["created_at", Mon, 03 Sep 2012 21:35:53 UTC +00:00], ["email", nil], ["first", "John"], ["last", "Doe"], ["updated_at", Mon, 03 Sep 2012 21:35:53 UTC +00:00], ["uuid", nil]]
(43.5ms) commit transaction
=> #<Person id: 1, email: nil, first: "John", last: "Doe", uuid: nil, book_id: nil, created_at: "2012-09-03 21:35:53", updated_at: "2012-09-03 21:35:53">
1.9.3p194 :005 > book = Book.create!( {:title => "Ruby for Dummies"} )
(0.1ms) begin transaction
SQL (1.4ms) INSERT INTO "books" ("blurb", "created_at", "person_id", "published", "title", "updated_at") VALUES (?, ?, ?, ?, ?, ?) [["blurb", nil], ["created_at", Mon, 03 Sep 2012 21:36:25 UTC +00:00], ["person_id", nil], ["published", nil], ["title", nil], ["updated_at", Mon, 03 Sep 2012 21:36:25 UTC +00:00]]
(4.4ms) commit transaction
=> #<Book id: 1, blurb: nil, published: nil, title: nil, person_id: nil, created_at: "2012-09-03 21:36:25", updated_at: "2012-09-03 21:36:25">
1.9.3p194 :006 > person.books << book
(0.1ms) begin transaction
(0.3ms) UPDATE "books" SET "person_id" = 1, "updated_at" = '2012-09-03 21:36:39.566387' WHERE "books"."id" = 1
(4.4ms) commit transaction
Book Load (0.3ms) SELECT "books".* FROM "books" WHERE "books"."person_id" = 1
=> [#<Book id: 1, blurb: nil, published: nil, title: nil, person_id: 1, created_at: "2012-09-03 21:36:25", updated_at: "2012-09-03 21:36:39">]
1.9.3p194 :007 > Book.all
Book Load (0.5ms) SELECT "books".* FROM "books"
=> [#<Book id: 1, blurb: nil, published: nil, title: nil, person_id: 1, created_at: "2012-09-03 21:36:25", updated_at: "2012-09-03 21:36:39">]
The problem is with your Book model, try the following:
class Book < ActiveRecord::Base
attr_accessible :person, :title, :person
belongs_to :person
end
Before:
1.9.3p194 :002 > Book.last
Book Load (0.1ms) SELECT "books".* FROM "books" ORDER BY "books"."id" DESC LIMIT 1
=> #<Book id: 4, blurb: nil, published: nil, title: nil, person_id: 1, created_at: "2012-09-03 21:55:33", updated_at: "2012-09-03 21:55:33">
1.9.3p194 :003 > Book.last.person
Book Load (0.2ms) SELECT "books".* FROM "books" ORDER BY "books"."id" DESC LIMIT 1
=> nil
After:
1.9.3p194 :001 > Book.last
Book Load (0.4ms) SELECT "books".* FROM "books" ORDER BY "books"."id" DESC LIMIT 1
=> #<Book id: 4, blurb: nil, published: nil, title: nil, person_id: 1, created_at: "2012-09-03 21:55:33", updated_at: "2012-09-03 21:55:33">
1.9.3p194 :002 > Book.last.person
Book Load (1.0ms) SELECT "books".* FROM "books" ORDER BY "books"."id" DESC LIMIT 1
Person Load (0.1ms) SELECT "people".* FROM "people" WHERE "people"."id" = 1 LIMIT 1
=> #<Person id: 1, email: nil, first: "John", last: "Doe", uuid: nil, created_at: "2012-09-03 21:48:02", updated_at: "2012-09-03 21:48:02">

Answer 2

Have you tried doing something like the following? If so, what does book.person give you?
person = Person.create!( {:first => "John", :last => "Doe"} )
book = Book.create!( {:title => "Ruby for Dummies"} )
book.person_id = person.id
person.books
book.person