Rails嵌套连接

Question

制造商

has_many :product

产品

has_many :part

PartsRequest

belongs_to :part
belongs_to :manufacturer 

我正在尝试在PartsRequest中做一些事情 例如制造商A正在尝试从制造商B请求零件

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

如何加入零件，然后从零件加入产品？

Answer 1

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