问Rails 4急切加载(关联与方法)的效率

EN

  # application_controller

  def active_students # 1 query
    # used by simply calling active_students
    Account.includes(:role, {user: :school}).where(status: 0).where("roles.name = ?", 'student').where("users.school_id = ?", current_school.id).references(:role, :user, :school)
  end

  # school.rb
  # used by calling current_school.active_students
  # 125 queries

  has_many :active_students, -> { joins(:role).where( "roles.name = ? AND accounts.status = ?", "student", 0 ) }, source: :accounts, through: :users