ActiveRecord“has_aggregate”元编程功能？

Question

那里有什么提供“has_aggregate”元编程功能吗？

例如，假设您有一个提供以下方法的模型：

class Customer < ActiveRecord::Base

  has_many :orders

  def total_orders
    orders.count
  end

  def total_spent
    orders.sum(:total_amount)
  end

end

ActiveRecord（或gem）中是否有任何允许语法类似的功能？

class Customer < ActiveRecord::Base

  has_many :orders

  has_aggregate :total_orders, :orders, :count

  has_aggregate :total_spent, :orders, :sum, :total_amount

end