的Rails 3態關聯養NameError

Question

我有以下2種型號：

class FuzzyDate < ActiveRecord::Base 
    belongs_to :fuzzy_dateable, :polymorphic => true 
end 

class Device < ActiveRecord::Base 
    has_one :received_date, :as => :fuzzy_dateable 
end 

與下面的模式：

create_table "devices", :force => true do |t| 
    t.string "meid" 
    t.datetime "created_at" 
    t.datetime "updated_at" 
    end 

    create_table "fuzzy_dates", :force => true do |t| 
    t.date  "date" 
    t.integer "fuzz" 
    t.integer "fuzzy_dateable_id" 
    t.string "fuzzy_dateable_type" 
    t.datetime "created_at" 
    t.datetime "updated_at" 
    end 

我們啓動控制檯，好嗎？

>> d = Device.create(:meid => "A") 
=> #<Device id: 1, meid: "A", created_at: "2010-12-16 06:52:55", updated_at: "2010-12-16 06:52:55"> 
>> fd = FuzzyDate.create(:date => Date.today, :fuzz => 3) 
=> #<FuzzyDate id: 1, date: "2010-12-15", fuzz: 3, fuzzy_dateable_id: nil, fuzzy_dateable_type: nil, created_at: "2010-12-16 06:53:04", updated_at: "2010-12-16 06:53:04"> 
>> fd.fuzzy_dateable = d 
=> #<Device id: 1, meid: "A", created_at: "2010-12-16 06:52:55", updated_at: "2010-12-16 06:52:55"> 
>> fd 
=> #<FuzzyDate id: 1, date: "2010-12-15", fuzz: 3, fuzzy_dateable_id: 1, fuzzy_dateable_type: "Device", created_at: "2010-12-16 06:53:04", updated_at: "2010-12-16 06:53:04"> 

好的，到目前爲止，這麼好。我們從另一個方向走：

>> d.received_date 
NameError: uninitialized constant Device::ReceivedDate 
     from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/base.rb:1199:in `compute_type' 
     from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/reflection.rb:162:in `send' 
     from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/reflection.rb:162:in `klass' 
     from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/reflection.rb:198:in `quoted_table_name' 
     from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations/has_one_association.rb:97:in `construct_sql' 
     from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations/has_one_association.rb:7:in `initialize' 
     from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations.rb:1450:in `new' 
     from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.3/lib/active_record/associations.rb:1450:in `received_date' 
     from (irb):5 
>> 

Doh！我做了一堆Googleing，我發現的答案都是錯誤地使用複數模型名稱的方式，這裏不是這種情況。我已經度過了幾個晚上我的頭反對這個，所以任何指導將不勝感激。

Answer 1

這裏的問題是，在您的設備模型中，您將關聯名稱命名爲：received_date，並且默認情況下會查找ReceivedDate模型，除非您另行說明。

我想說你可以選擇其中任何一種解決方案。

1號

class Device < ActiveRecord::Base 
    has_one :received_date, :as => :fuzzy_dateable, :class_name => "FuzzyDate" 
end 

2號

class Device < ActiveRecord::Base 
    has_one :fuzzy_date, :as => :fuzzy_dateable 
end