Rails nested_attributes不能用于has_many

Question

我有三个模特

用户：

class User < ApplicationRecord
    has_many :provider_contracts, :class_name => "Contract", :dependent => :destroy
    has_many :provider_users, :class_name => "User", :through => :provider_contracts

    has_many :customer_contracts, :class_name => "Contract", :dependent => :destroy
    has_many :customer_users, :class_name => "User", :through => :customer_contracts

    has_one :profile, :dependent => :destroy

    accepts_nested_attributes_for :profile
end

合同：

class Contract < ApplicationRecord
    belongs_to :provider_user, :class_name => "Node", :inverse_of => :customer_contracts
    belongs_to :customer_user, :class_name => "Node", :inverse_of => :provider_contracts
end

资料：

class Profile < ApplicationRecord
    belongs_to :user
end

现在我创建了一个用户名A，我想将一个客户添加到A：

user_a = User.create(:name => "A", :profile_attributes => {:company_name => "A Company"})
# success with profile
user_b = user_a.customer_users.new(:name => "B", :profile_attributes => {:company_name => "B Company"})
user_b.save
# success with contract but profile

结果是：

创建用户A并使用正确的配置文件

创建用户B

用户A和用户B具有正确的合同

但是B的配置文件是在没有user_id的情况下创建的，因此不会创建关联。

请帮助，谢谢！