Belongs_to. Association methods don't pass data to DB

Rails
1

Hi.

I have a problem with the association methods which passed to a model
through a belongs_to declaration. Here’s an illustration of the issue:

GIVEN:

migration

class CreateArticlesAndAuthorsTables < ActiveRecord::Migration
def self.up
create_table :articles do |t|
t.text :title
t.integer :author_id
end

create_table :authors do |t|
  t.text :name
end

end

def self.down
drop_table :articles
drop_table :authors
end
end

articles model

class Article < ActiveRecord::Base
belongs_to :author
end

authors model

class Author < ActiverRecord::Base
has_many :articles
end

WHEN:

Article.create(:title => ‘one’).author = Author.create(:name => ‘Pavel’)

Article.create(:title => ‘two’).author = Author.find(:first, :conditions => {:name => ‘Pavel’})

THEN

sqlite> select * from authors;
id = 1
name = Pavel

sqlite> select * from articles;
id = 1
title = ‘one’
author_id = null

       id = 2
    title = 'two'

author_id = null

Why do I have null values instead of ids as foreign keys in the
articles table?

Thanks.

Ruby 1.9.2;
Rails 2.3.8.

2

I got it.

It should to break the creation statements onto a few steps:

WHEN:

one = Article.new(:title => ‘one’)

one.author = Author.new(:name => ‘Pavel’)

one.save

two = Article.new(:title => ‘two’)

two.author = Author.find(:first, :conditions => {:name => ‘Pavel’})

two.save

THEN:

sqlite> select * from authors;
id = 1
name = Pavel

sqlite> select * from articles;
id = 1
title = ‘one’
author_id = 1

       id = 2
    title = 'two'

author_id = 1

3

I was most interested about that methods which are added by belongs_to
declaration not has_many.

Anyway, thanks for help, Colin.

4

On 29 June 2010 17:29, P.A. [email protected] wrote:

one.save

two = Article.new(:title => ‘two’)

two.author = Author.find(:first, :conditions => {:name => ‘Pavel’})

two.save

Have a look at
author.articles.build
which will build a new article for an author and save some messing
about.

Colin