重构代码以避免N+1查询

Question

我有这样的协会

models/transcription.rb

class Transcription < ActiveRecord::Base
  belongs_to :transcription_status, :class_name => "TranscriptionStatus",
    :inverse_of => :transcriptions


  # Initialize to "new" status if a status isn't already set
  def setup_status
    if transcription_status.nil?  # this method is taking lots of execution time ( N + 1 )
      status = TranscriptionStatus.find_by_state("new")
      if status
        self.transcription_status = status
      end
    end
  end
end

models/transcription_status.rb

class TranscriptionStatus < ActiveRecord::Base
  has_many :transcriptions, :inverse_of => :transcription_status
end

问题

每次我调用transcription_status时，它都在执行N+1查询。建议我如何重构这段代码以防止N+1查询限制？

谢谢

Answer 1

必须使用includes预加载数据：

Transscription.includes(:transcription_status)