手动管理关联可以吗?

不,这不是一个ruby方式,虽然你没有编辑顺序一旦创建。

在模型中使用以下关系,我认为它会起作用。但没有支票

User.rb
has_many :users
has_many :purchase, :class_name =>Order, :foreign_key=>'buyer_id'
has_many :sells, :class_name =>Order, :foreign_key=>'seller_id'

Product.rb
belongs_to :user
has_many :orders

Order.rb
belongs_to :buyer, :class_name =>User, :foreign_key=>'buyer_id'
belongs_to :seller, :class_name =>User, :foreign_key=>'seller_id'
belongs_to :product

您应该为此使用Rails关联。这个 has_many 对于您的场景,关联是一个更好的选择。

class User < ActiveRecord::Base
  has_many :buys,  :class_name => "Order", :foreign_key => "buyer_id"
  has_many :sales, :class_name => "Order", :foreign_key => "seller_id"
end

class Product < ActiveRecord::Base
end

class Order < ActiveRecord::Base
  belongs_to :product
  belongs_to :buyer,  :class_name => "User", :foreign_key => "buyer_id"
  belongs_to :seller, :class_name => "User", :foreign_key => "seller_id"
end

现在可以按如下方式使用关联:

current_user.buys.create(:seller => u, :product => p)
current_user.buys
current_user.sells