ruby-on-rails – Rails 4：未定义的方法`primary_key_name’

NoMethodError: undefined method `primary_key_name' for #<ActiveRecord::Reflection::AssociationReflection

使用Rails 3.2.x时,我没有得到异常.

我在Rails 3.2.13和Rails 4.0.0.beta上使用Ruby 1.9.3-p194.

问题源于以下has_many声明：

class Store < ActiveRecord::Base
  has_many :relationships
  has_many :customers,:through => :relationships,:source => :user,:conditions => { :relationships => { :description => "Customer" } } do
      def <<(user)
        proxy_association.owner.relationships.create(:description => "Customer",:user => user)
      end
    end
end

我有以下支持课程：

class User < ActiveRecord::Base
  has_one :relationship
  has_one :store,:through => :relationship
end

class Relationship < ActiveRecord::Base
  belongs_to :store
  belongs_to :user
end

我想知道如何使用Rails 4友好代码实现相同的has_many功能？

附：我知道我仍然使用旧式语法,条件哈希现在需要proc或lambda,但这些不应该导致未定义的方法异常.