Question

I have three models: RaceCards, Races and Wagers.

class RaceCard < ActiveRecord::Base
has_many :races
has_many :wagers
end

class Race < ActiveRecord::Base
belongs_to :race_card
has_many :wagers, :through => :race_card
end

class Wager < ActiveRecord::Base
belongs_to :race_card
has_many :races, :through => :race_card
end

rails g model RaceCard race_card_date:date number_of_race:integer

rails g model Race race_card_id:integer race_nbr:integer

rails g model Wager race_nbr:integer race_card_id:integer wager_type:string payoff:integer

So if I do this in console:

Wager.first.races  #All races on the race card are returned. Good!

But I want a way of determining what races are returned so I add a condition:

if I add this:   :condition =>{:race_nbr => 1}

Wager.first.races  #Return just race 1, but this is static (always set to 1)

My question is how do I set the condition to the race_nbr in the Wager model:

:condition => {:race_nbr => wager.race_nbr}  #throws an error
:condition => {:race_nbr => self.race_nbr}   #throws an error

I’ve tried a lot of other things and just can’t seem to get it. Any guidance would be appreciated. Thanks in advance.

Update: I’ve now tried the solution suggested by PinnyM below

:condition => "wagers.race_nbr = races.race_nbr" #unfortunately this yields the following:

SQL error or missing database (no such column wagers.race_nbr)

Answer 1

You can do this using scopes:

def Race < ActiveRecord::Base
  scope :for_race_nbr, lambda { |race_nbr| where(:race_nbr => race_nbr) }
end

def Wager < ActiveRecord::Base
  def races_for_race_nbr
    races.for_race_nbr(race_nbr)
  end
end