Blaine, Thanks for the post. The book I'm reading followed up the basic join example (many-to-many) with a 'rich' join (has_many :through). From what I understand there's a scenario for both and they're similar but there are differences. In the book's example the articles and categories tables are 'meeting up' at the articles_categories table and not 'going through' to reference another table.
Thanks On Friday, January 24, 2014 4:39:28 PM UTC-5, Blaine LaFreniere wrote: > > > 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*: brlafr...@gmail.com <javascript:> > - *Web*: brlafreniere.com > > -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-talk+unsubscr...@googlegroups.com. To post to this group, send email to rubyonrails-talk@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/rubyonrails-talk/734daa7f-7ccb-40ea-bc5c-a81dfb4cb021%40googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
