如何通过3个模型的关联来提供has_many？

Question

I hope someone has already experienced this. Please help me, how can i solve this problem:

class Article < ActiveRecord::Base
  belongs_to :author
  belongs_to :publisher
  has_one :address, :through => :publisher
end

class Author < ActiveRecord::Base
  has_many :articles
  has_many :addresses, :through => :articles, :source => :address
end

I try to get "addresses" for "author", and i get this error in console:

ActiveRecord::HasManyThroughSourceAssociationMacroError: Invalid source reflection macro :has_one :through for has_many :addresses, :through => :articles.  Use :source to specify the source reflection.

but author.articles[0].address works fine.

I hope you give me advice, how can i solve it. Thanks.

Answer 1

AR does not like sourcing a has_many through a has_one . But you can easily get all the addresses with this method on Author :

def addresses
  articles.map {|article| article.address }
end

Answer 2

This solution also worked well for different relation types.

eg User.registrations.join_table.periods

but you -can't- apply active_record methods on what is mapped.

eg user.periods(:order => :date) eg user.periods.model etc..

thanks