I’m trying to avoid the N+1 queries problem with eager loading, but
it’s not working. The associated models are still being loaded
individually.
Here are the relevant ActiveRecords and their relationships:
class Player < ActiveRecord::Base
has_one :tableau
end
Class Tableau < ActiveRecord::Base
belongs_to :player
has_many :tableau_cards
has_many :deck_cards, :through => :tableau_cards
end
Class TableauCard < ActiveRecord::Base
belongs_to :tableau
belongs_to :deck_card, :include => :card
end
class DeckCard < ActiveRecord::Base
belongs_to :card
has_many :tableaus, :through => :tableau_cards
end
class Card < ActiveRecord::Base
has_many :deck_cards
end
and the query I’m using is inside this method of Player:
def tableau_contains(card_id)
self.tableau.tableau_cards = TableauCard.find :all, :include =>
[ {:deck_card => (:card)}], :conditions => [‘tableau_cards.tableau_id
= ?’, self.tableau.id]
contains = false
for tableau_card in self.tableau.tableau_cards
# my logic here, looking at attributes of the Card model,
with
# tableau_card.deck_card.card
# card is the model being loaded repeatedly and individually,
after being loaded with the TableauCard.find :include
end
return contains
end
Does it have to do with scope? This method is down a few calls in a
larger loop in an observer, where I originally tried doing the eager
loading because there are several places where these same objects are
looped through and examined. In that observer, I load a @game object,
and then load @game.players.
I eventually tried the code as it is above, with the load just before
the loop, and I’m still seeing the individual SELECT queries for the
individual cards objects inside the tableau_cards loop in the log. I
can see the eager-loading query with the IN clause just before the
tableau_cards loop as well.