On 1/24/14, 11:25 AM, Martin Sloan wrote:
Hello,
I'm new to Ruby/Rails and going through 'Beginning Rails 4'. In
chapter 6 it has me create a join table for an articles and categories
table (articles_categories). In the migrate file I've entered this
code from the book:
class CreateArticlesCategories < ActiveRecord::Migration
def change
create_table :articles_categories, :id=> false do |t|
t.references :article
t.references :category
end
end
def self.down
drop_table :articles_categories
end
end
My issue is that after I migrate this file, when I try to make an
association between the article and category object
(article.categories << category) it spits an error that article_id
does not exist in articles_categories table. It makes sense to me
since the references above do no have _id appended in the class. If I
change the class to the following, creating the relationship between
article and category works fine:
class CreateArticlesCategories < ActiveRecord::Migration
def change
create_table :articles_categories, :id=> false do |t|
t.integer :article_id
t.integer :category_id
end
end
def self.down
drop_table :articles_categories
end
end
My question is, how can I get the 't.references' format to work so
that AR looks for an 'articles' and 'categories' column, instead of
the same with _id appended?
You need to use has_many :through when working with join tables, not
has_and_belongs_to_many. The :through parameter specifies the join table.
See this section of the Rails guide:
http://guides.rubyonrails.org/association_basics.html#the-has-many-through-association
--
* Blaine LaFreniere
* *Phone*: 801-448-6124
* *E-mail*: [email protected]
* *Web*: brlafreniere.com <http://brlafreniere.com>
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