Rails ActiveRecord has_one和belongs_to重新加载关联

Question

I have four models

class Votation
  belongs_to :quorum

  def calc
    return self.quorum.calc
  end

end

class Quorum
  has_one :votation
  ...
end

class NewQuorum < Quorum
  def calc
    do stuff and call
    self.votation.attribute_a
  end
end

class OldQuorum < Quorum
  def calc
    do stuff and call
    self.votation.attribute_b
  end
end

I have loaded the votation into a @votation object and eager loaded the associated Quorum.

The problem is that when I call @votation.calc , ActiveRecord execute a SQL select to load the votation again when it has to execute self.votation.attribute_a for example.

SELECT "votations".* FROM "votations" WHERE "votations"."quorum_id" = $1

how can I avoid this select from being executed?

Answer 1

You can use the :inverse_of option when specifying the association to prevent another select statement from being executed.

So your models would look like:

 class Votation
   belongs_to :quorum, inverse_of: :votation
 end

 class Quorum
   has_one :votation, inverse_of: :quorum
 end

Reference: http://apidock.com/rails/ActiveRecord/Associations/ClassMethods/belongs_to