通過HAS_ONE訪問一個belongs_to的關聯模型：通過

Question

我似乎無法找出爲什麼這個協會是不工作：我不知道怎麼形容不是提供代碼示例更好的情況：

這裏是我的應用環境：

Ruby version    1.8.7 (universal-darwin10.0) 
Rails version    2.3.3 

和代碼示例：

class Account 
has_one :subscription 
has_one :package, :through => :subscription 
end 

class Subscription 
belongs_to :account 
belongs_to :package 
end 

class Package 
has_many :subscriptions 
has_many :accounts, :through => :subscriptions 
end 

>> Account.first.subscription 
=> #<Subscription id: 1, account_id: 25, package_id: 4> 

>> Account.first.subscription.package 
=> #<Package id: 4, name: "Bronze Package"> 

>> Package.first.accounts 
=> [#<Account id: 25, subdomain: "bigbangtechnology">] 

>> Package.first.subscriptions 
=> [#<Subscription id: 1, account_id: 25, package_id: 4>] 

>> Account.first.package 
    Package Load (0.0ms) Mysql::Error: Unknown column 'packages.account_id' in 'where clause': SELECT `packages`.* FROM `packages` WHERE (packages.account_id = 25) 
ActiveRecord::StatementInvalid: Mysql::Error: Unknown column 'packages.account_id' in 'where clause': SELECT `packages`.* FROM `packages` WHERE (packages.account_id = 25) 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:212:in `log' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:320:in `execute' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:595:in `select' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all_without_query_cache' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:62:in `select_all' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/base.rb:661:in `find_by_sql' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/base.rb:1548:in `find_every' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/base.rb:615:in `find' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/associations/has_many_through_association.rb:73:in `find_target' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/associations/has_one_through_association.rb:23:in `find_target' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/associations/association_collection.rb:353:in `load_target' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/associations/association_proxy.rb:112:in `reload' 
from /Users/camwest/Sites/yardstickapp/vendor/rails/activerecord/lib/active_record/associations.rb:1219:in `package' 
from (irb):22 

Answer 1

鐵軌的2.2.1您可以使用委託：

class Account 
    delegate :package, :to => :subscription 
end

http://apidock.com/rails/Module/delegate

Answer 2

看起來像我發現我的答案通過文檔閱讀：

：通過

指定加入通過模型來進行查詢。選項：class_name和：foreign_key被忽略，因爲關聯使用源反射。您只能在連接模型上使用通過has_one或belongs_to關聯的通過查詢。

這告訴我的是，除了訂閱模型（我的連接模型）之外，您無法使用：通過has_one。吮！如果任何人有任何其他的答案，那就太好了。