如何在Ruby on Rails中的嵌套模型关联上使用选择方法

Question

I have three models:

class Person
  has_many :houses
end

class House
  belongs_to :person
  has_many :appliances

  attr_accessible :address
end

class Appliance
  belongs_to :house

  attr_accessible :price
end

I want to use the 'select' method to fetch only the 'price' values such as the following:

Person.joins(:houses => :appliances).select('houses.appliances.price')

But the above didn't work. However, I tested a similar method like the one below that works:

Person.joins(:houses).select('houses.address')

Any help would be much appreciated.

Answer 1

我想这应该工作：

Person.joins(houses: :appliances).select('appliances.price')