Association through 2 intermediate Models

rubyonrails-talk
1

Hey,

I have an association chain like this:

Site has_many Feed(s) has_many FeedEntry(/ies) has_many Articles

where the reverse is always belongs_to:

Article belongs_to FeedEntry belongs_to Feed belongs_to Site

Now what I want is to get all articles that belong to a specific Site, something like Site.first.articles

I can't figure out how to do this, or if it's possible with has_many :through Can anyone give me a hint please?

Thank you

2

sorry, what?

3

sorry, what?

you can use through na…

Hi, I recommend reading AWDwR 3ed on using ‘has_many through’ for the details.

Good luck,

-Conrad

4

Hi,

5

perhaps the responses could be a bit more helpful here?

sol,

I have done it through 2 level associations using through

eg.

Sites

has_many :feed_entries, :through=>:feeds

I have tried with 3 levels, but never got it to work, ie, how do you chain the throughs. I have tried to make sure that the through is in place at each level, but to no avail.

Perhaps someone may be able to enlighten us.

Tonypm

6

I don't know if you can get there just w/HM=>T, but you can fake out the last link w/a custom method. This is working for me:

class Article < ActiveRecord::Base   belongs_to :feed_entry end

class FeedEntry < ActiveRecord::Base   belongs_to :feed   has_many :articles end

class Feed < ActiveRecord::Base   belongs_to :site   has_many :feed_entries   has_many :articles, :through => :feed_entries end

class Site < ActiveRecord::Base   has_many :feeds   def articles     arts =     self.feeds.each do |f|       arts << f.articles     end     # Not sure if that uniq call is necessary...     arts.flatten.uniq   end end

That gives me a my_site.articles collection which returns the union of all articles attached to any feed_entry attached to any feed attached to the Site.

HTH,

-Roy