Ruby on Rails four-way association tree

问题

The big picture: I am creating an app to track temporal events historically. I am setting it up with four main models: Users, Events, Stories and Images. The idea is that any given user can create an Event, and add Stories and/or Images to his own Event or to any other one. But both Stories and Images are always attached to a certain Event, and any other model belongs to the User who created it (for filtering and editing purposes)

The general structure of the associations would be something like this:

class User < ActiveRecord::Base
  has_many :events
  has_many :stories
  has_many :images
end

class Event < ActiveRecord::Base
  belongs_to :user
  has_many :stories
  has_many :images
end

class Story < ActiveRecord::Base
  belongs_to :user
  belongs_to :event
end

class Image < ActiveRecord::Base
  belongs_to :user
  belongs_to :event
end

I am kind of new to Rails and I have little-to-no control over more complex associations as many_to_many, through: or as:

My question here is, is this set of associations optimal, or could it be improved by combining them in a different way?

回答1:

You're in the right track, but story and image shouldn't belong to user. You're creating a redundancy in there.

class User < ActiveRecord::Base
  has_many :events
  has_many :stories, :through => :events
  has_many :images, :through => :events
end

class Event < ActiveRecord::Base
  belongs_to :user
  has_many :stories
  has_many :images
end

class Story < ActiveRecord::Base
  belongs_to :event
end

class Image < ActiveRecord::Base
  belongs_to :event
end

This way you can still write user.stories and user.images.

回答2:

Try to use nested attributes:

http://railscasts.com/episodes/196-nested-model-form-part-1

Sample code:

class User < ActiveRecord::Base
  has_many :events
  accepts_nested_attributes_for :events
end

class Event < ActiveRecord::Base
  belongs_to :user
  has_many :stories
  has_many :images
  accepts_nested_attributes_for :stories, :images
end

class Story < ActiveRecord::Base
  belongs_to :event
end

class Image < ActiveRecord::Base
  belongs_to :event
end

Nested attributes accepts many level. In this case, there are 3 levels