检查模型上的关系表，轨道上的红宝石

Question

我在 Rails 3.2.14 上有 ruby​​ 项目。我有 2 个名为“国家”和“用户”的表。在“用户”表中有名为“countries_id”的 FK。 在模型上，我使表关系如下： 在countries.rb 我设置了如下关系：

class Countries < ActiveRecord::Base
  self.primary_key = "id"
  has_many  :users,  :dependent => :destroy # plural
end

在 users.rb 中像：

class Users < ActiveRecord::Base
  self.primary_key = "id"


  belongs_to    :countries,
                :class_name => "Countries",
                :foreign_key => "countries_id"

end

当我想检查复数关系时，它没有.. 我像下面一样输入rails控制台命令

c=Countries.find_by_id(1)

然后当我输入命令 u=c.users 时，我有一些错误 错误：

c=Countries.find_by_id(1)
  Countries Load (0.3ms)  SELECT `countries`.* FROM `countries` WHERE `countries`.`id` = 1 LIMIT 1
 => #<Countries id: 1, code: "IND", name: "Indonesia", created_at: "2014-02-17 09:18:11", updated_at: "2014-02-17 09:18:11"> 
1.9.3-p484 :012 > u=c.users
NameError: uninitialized constant Countries::User
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/activerecord-3.2.14/lib/active_record/inheritance.rb:111:in `compute_type'
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/activerecord-3.2.14/lib/active_record/reflection.rb:172:in `klass'
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/activerecord-3.2.14/lib/active_record/associations/association.rb:118:in `klass'
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/activerecord-3.2.14/lib/active_record/associations/association.rb:171:in `find_target?'
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/activerecord-3.2.14/lib/active_record/associations/collection_association.rb:334:in `load_target'
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/activerecord-3.2.14/lib/active_record/associations/collection_proxy.rb:44:in `load_target'
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/activerecord-3.2.14/lib/active_record/associations/collection_proxy.rb:87:in `method_missing'
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/railties-3.2.14/lib/rails/commands/console.rb:47:in `start'
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/railties-3.2.14/lib/rails/commands/console.rb:8:in `start'
    from /home/vinra/.rvm/gems/ruby-1.9.3-p484@rails3.2/gems/railties-3.2.14/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'
1.9.3-p484 :013 > ^C
1.9.3-p484 :013 >

我真的希望有人知道我的问题， 无论如何谢谢你，对不起我的英语不好:)

Answer 1

你应该在你的代码中改变很多东西：

app/models/country.rb

class Country < ActiveRecord::Base
    has_many :users, :dependent => :destroy
end

app/models/user.rb

class Users < ActiveRecord::Base
    belongs_to :country,
               :foreign_key => "countries_id"
end

并像这样使用它：

country = Country.find(1)
p country.users

Answer 2

问题是 Rails Active Record 模型不能是复数。您使用复数创建了模型，因此将它们更改为单数或更好的方法是使用单数名称再次创建它们。

Countries 应该是 Country 和 Users 应该是 User。

有关命名约定的更多信息，请参阅This。

希望对你有帮助！