ruby on rails 3 - How to change these SQL statements with multiple joins into ActiveRecord style queries? -

artists have_many :posts, posts have_many :comments. artists follow other artists through "inspirations". (i want build facebook-type news-feed show recent activity such as:)

• someone has posted new comment on 1 of posts
• artist whom follow has added new post
• artist whom follow received new comment on particular post

my idea 3 independent queries above, , concatenate final messages desc date. here how 3 queries, using methods in artist class:

 def comments_on_my_posts    comment.where(:joins => :post, :conditions => {:posts => {:artist_id => 1}}).order("comments.updated_at desc")  end   def posts_from_my_follows    #select * posts inner join inspirations on posts.artist_id = inspirations.author_id inspirations.artist_id = self.id    #  end   def comments_on_posts_on_people_i_follows    # select * comments inner join posts on comments.post_id = posts.id inner join inspirations on posts.artist_id = inspirations.author_id inspirations.artist_id = self.id  end 

i prefer not use sql directly if don't have to. don't know how multiple joins using activerecord.

for reference, here models:

class artist < activerecord::base    has_many :posts, :dependent => :destroy, :order => 'updated_at desc'   has_many :inspirations   has_many :follows, :through => :inspirations, :source => :inspiration  end   class post < activerecord::base    belongs_to :artist   has_many :comments, :dependent => :destroy, :order => 'updated_at desc'   end  class comment < activerecord::base    belongs_to :author, :class_name => "artist", :foreign_key => :author_id   belongs_to :post  end  class inspiration < activerecord::base    #the follower   belongs_to :artist    #the followee   belongs_to :inspiration, :class_name => 'artist', :foreign_key => :author_id    validate :disallow_self_referential_following    validates_uniqueness_of :artist_id, :scope => :author_id    def disallow_self_referential_following     if artist_id == author_id     errors.add(:author_id, 'cannot follow self')   end end 

the rails 3 query interface joins documented here: http://guides.rubyonrails.org/active_record_querying.html#specifying-conditions-on-the-joined-tables.

with rails 3 can chain activerecord calls build query want. sure watch development log file see queries being generated. (unless you're on rails 3.1 version). can add .to_sql call end of query see generates.