Rails的嵌套的联接

Question

厂商

has_many :product 

产品

has_many :part 

PartsRequest

belongs_to :part 
belongs_to :manufacturer 

我试图做一些PartsRequest 例如制造商A正试图从制造商B处获得零件请求如何加入零件，然后从零件加入产品中？

Answer 1

scope :incoming_requests, lambda{|mid| joins(:part => :product).where(:product => {:manufacturer_id => mid}) }