Rails Ruby on Rails

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• 

  Andrew White March 23rd, 2011 @ 06:09 PM

  • State changed from “new” to “open”
  • Assigned user set to “Andrew White”
  • Importance changed from “” to “Low”

  Yep, I've confirmed this - if you define the association in the base class it works as expected though.

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  eli.b March 23rd, 2011 @ 06:17 PM

  Hey-
  Thanks Andrew!
  'if you define the association in the base class it works as expected though.' What do you mean exactly? If I just put the class definition of Third inside second.rb? Sorry, I'm a little new to the not-so-simple associations game.
  -e

• 

  Andrew White March 24th, 2011 @ 11:59 AM

  Using your models it would be like this:

  class First < ActiveRecord::Base
    has_many :tags
    has_many :seconds, :through => :tags
  end
  
  class Second < ActiveRecord::Base
    has_many :tags
    has_many :firsts, :through => :tags
  end
  
  class Third < Second; end
  
  class Tag < ActiveRecord::Base
    belongs_to :first
    belongs_to :seconds
  end
  

  Setting it up this way will return the appropriate models when use First.joins(:seconds).where(:seconds => { :id => 1 }). Using more descriptive model names will make it clearer:

  class Vehicle < ActiveRecord::Base
    has_many :taggings
    has_many :tags, :through => :taggings
  end
  class Car < Vehicle; end
  class Van < Vehicle; end
  class Motorbike < Vehicle; end
  
  class Tag < ActiveRecord::Base
    has_many :taggings
    has_many :vehicles, :through => :taggings
  end
  
  class Tagging < ActiveRecord::Base
    belongs_to :vehicle
    belongs_to :tag
  end
  
  >> Tag.joins(:vehicles).where("vehicles.id = 1").to_sql
  => "SELECT tags.* FROM tags INNER JOIN taggings ON tags.id = taggings.tag_id INNER JOIN vehicles ON taggings.vehicle_id = vehicles.id WHERE vehicles.id = 1"