ruby-on-rails - has_many :though (undefined method class_name for nil:NilClass) 的 NoMethodError

Question

最近，当我调用 organization.subscriptions 上的任何方法时，我遇到了 NoMethodError

NoMethodError at /organizations/1
undefined method `class_name' for nil:NilClass
Did you mean?  class_eval

看起来 class_name 是在不存在的东西上调用的。但由于有交易和订阅，这种情况不应该发生。我一直盯着我的代码，但我看不到错误。有人可以帮忙吗？

# organization.rb
class Organization < ApplicationRecord
  has_many :deals
  has_many :subscriptions, through: :deals, source: :initialized_subscriptions
end

# deal.rb
class Deal < ApplicationRecord
  belongs_to :organization
  has_many :initialized_subscriptions, foreign_key: :initial_deal_id, class_name: 'Subscription'
end

# subscription.rb
class Subscription < ApplicationRecord
  belongs_to :initial_deal, class_name: 'Deal'
end

这是表格

organizations    
+----+----------+
| id |   name   |
+----+----------+
|  1 | Org name |
+----+----------+

deals
+----+------------+-----------------+
| id |    name    | organization_id |
+----+------------+-----------------+
|  1 | First Deal |               1 |
+----+------------+-----------------+

subscriptions
+----+-----------------+
| id | initial_deal_id |
+----+-----------------+
|  1 |               1 |
+----+-----------------+

非常感谢各位的帮助!

Answer 1

这是一个盲目的尝试，但我认为 Rails 在您的 has_many 关联中假定了不同的类名。

# In this case, Rails assumes class_name: 'Subscription'
has_many :subscriptions

# In this case, Rails also assumes class_name: 'Subscription'
has_many :subscriptions, through: :deals

# But in this case, I think Rails assumes class_name: 'InitializedSubscription'
has_many :subscriptions, through: :deals, source: :initialized_subscriptions

也许可以试试这个

has_many :subscriptions, through: :deals,
                         source: :initialized_subscriptions,
                         class_name: 'Subscription'