Creating Rails associations

I'm having a hard time understanding how to create the following associations:

User has many photo albums
Photo Album has many photos
Users can follow someone else's specific photo album (and indirectly they end up following the photo album's owner) and have the photos show up in a "news feed" type scenario, so there has to be some sort of relationship set up between them

Here's the associations I have:

class User < ActiveRecord::Base
  has_many :photo_albums
  has_many :photos
  has_many :relationships, :foreign_key => "follower_id", 
                           :dependent => :destroy
  has_many :reverse_relationships, :foreign_key => "followed_id", 
                                   :class_name => "Relationship", 
                                   :dependent => :destroy
  has_many :followings, :through => :relationships, :source => :followed
  has_many :followers, :through => :reverse_relationships, :source => :follower
end

class PhotoAlbum < ActiveRecord::Base
  belongs_to :user
  has_many :photos
end

class Photo < ActiveRecord::Base
  belongs_to :user
  belongs_to :photo_album
end

class Relationship < ActiveRecord::Base
  belongs_to :follower, :foreign_key => "follower_id", :class_name => "User"
  belongs_to :followed, :foreign_key => "followed_id", :class_name => "User"
end

How can I make it to where I can just get all the photos from the photo albums the user is following?

Example:

Jane has 2 photo albums, "Jane's Public Stuff" and "Jane's Private Stuff" with photos in each of them.
Bob follows ONLY "Jane's Public Stuff" so how can I return the photos from only that photo album via ActiveRecord associations?

Something like bob.followings.photos that returns photos from ONLY the photo albums that Bob is following... or even bob.followings.photo_albums to get a collection of all the photo albums that Bob is following

I know there's probably a long way to do this, but is there an easier way using ActiveRecord associations?

Thanks for any advice or guidance you can provide! I really appreciate it!

Upvotes: 1

Answers (3)

MrTheWalrus

Reputation: 9700

The way you have it set up, following associates a User to another User, not a User to a PhotoAlbum, which is what you describe. It sounds as though you want

class Relationship < ActiveRecord::Base
  belongs_to :follower, :foreign_key => "follower_id", :class_name => "User"
  belongs_to :followed, :foreign_key => "photo_album_id", :class_name => "PhotoAlbum"
end

With that done, a slight modification of davidb's answer should give you what you want:

def followings_photos
      Photo.where(:photo_album_id => self.followings.collect(&:id))
end

Upvotes: 2

davidb

Reputation: 8954

try this in User model:

def followings_photos
      Photo.where(:user_id => self.followings.collect(&:id))
end

Upvotes: 1

rocketscientist

Reputation: 2488

You may want to look at the amistad gem at https://github.com/raw1z/amistad, which gives you friends and friendships functionality. In your case, a friend would be a follower.

Then you can do something like user.friends.each do |f| to retrieve all the followers of user and then f.photos to get all the photos from each follower.

Upvotes: 1

Creating Rails associations

Answers (3)

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