Custom Association Method - Can This Be Done

Question

I have three models: Wager, Race, RaceCard and WagerType. I\'ve created a has_many association in Wagers and have added a custom association method (in_wager). The purpose

Answer 1

you can use self.proxy_association.owner to get the parent object inside of an association method. From there you can get the values you want.

If I understand your models correctly then the code should look something like this.

class Wager < ActiveRecord::Base
belongs_to :wager_type
belongs_to :race_card
  has_many :races, :through => :race_card do
    def in_wager
      owner = self.proxy_association.owner
      b = owner.race_nbr
      a = b - owner.wager_type.legs + 1
      where('races.race_nbr BETWEEN ? AND ?', a, b)
    end
  end
end

The I got this from the Rails api reference to Association Extensions (The reference to proxy_association is at the bottom of the section).

Answer 2

Do you absolutely need to use an has_many relation ? maybe you could just create a method in the Wager class

def races
  b = self.race_nbr
  a = b + self.race_card.legs
  Races.find_by_race_card_id(self.id).where('race_nbr BETWEEN ? AND ?', a, b)
end 

I don't really understand your model, so the request is certainly wrong, but you get the idea...