的Rails 3态关联养NameError

Question

我有以下2种型号：

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

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

与下面的模式：

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 

我们启动控制台，好吗？

>> 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，到目前为止，这么好。我们从另一个方向走：

>> 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，我发现的答案都是错误地使用复数模型名称的方式，这里不是这种情况。我已经度过了几个晚上我的头反对这个，所以任何指导将不胜感激。

Answer 1

这里的问题是，在您的设备模型中，您将关联名称命名为：received_date，并且默认情况下会查找ReceivedDate模型，除非您另行说明。

我想说你可以选择其中任何一种解决方案。

1号

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

2号

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