Rails：NameError：未初始化的常量 OrderItem

Question

models/order_item.rb

class OrderItem < ActiveRecord::Base    
  belongs_to :item
  belongs_to :order 
  belongs_to :user
end

models/order.rb

 class Order < ActiveRecord::Base   
     has_many :order_item
 end

现在，我使用rails console 测试这些。当我输入OrderItem 时，它抛出了

NameError: uninitialized constant OrderItem

更新

我是在 rails console 做的

2.1.3 :021 >   reload!
Reloading...
 => true 
2.1.3 :022 > Order
 => Order(id: integer, user_id: integer, created_at: datetime, updated_at: datetime, status: integer) 
2.1.3 :023 > Item
 => Item(id: integer, status: integer, name: string, price: integer, descript: text, created_at: datetime, updated_at: datetime, cover_file_name: string, cover_content_type: string, cover_file_size: integer, cover_updated_at: datetime, cate_id: integer) 
2.1.3 :024 > User
 => User(id: integer, email: string, encrypted_password: string, created_at: datetime, updated_at: datetime) 
2.1.3 :025 > OrderItem
NameError: uninitialized constant OrderItem
    from (irb):25
    from /Users/Coda/.rvm/gems/ruby-2.1.3@rails416/gems/railties-4.2.3/lib/rails/commands/console.rb:110:in `start'
    from /Users/Coda/.rvm/gems/ruby-2.1.3@rails416/gems/railties-4.2.3/lib/rails/commands/console.rb:9:in `start'
    from /Users/Coda/.rvm/gems/ruby-2.1.3@rails416/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:68:in `console'
    from /Users/Coda/.rvm/gems/ruby-2.1.3@rails416/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
    from /Users/Coda/.rvm/gems/ruby-2.1.3@rails416/gems/railties-4.2.3/lib/rails/commands.rb:17:in `<top (required)>'
    from /Users/Coda/Desktop/code/ruby_pra/shop/bin/rails:8:in `<top (required)>'
    from /Users/Coda/.rvm/rubies/ruby-2.1.3/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/Coda/.rvm/rubies/ruby-2.1.3/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from -e:1:in `<main>'

Answer 1

NameError: 未初始化的常量 OrderItem

has_many 的关联名称应该是plural，所以将order.rb 中的has_many :order_item 更改为has_many :order_items

#order.rb
class Order < ActiveRecord::Base   
  has_many :order_items #plural
end

更新：

在 github 上查看您的代码，order_item 和 .rb 之间有一个 空格，即 (order_item .rb)在文件名(app/models/order_item .rb)中。改成order_item.rb

Answer 2

鉴于 cmets，为了消除任何疑问，以下是我对 代码 的期望：

#app/models/order.rb
class Order < ActiveRecord::Base
   belongs_to :user #-> the order belongs to user, so if order_items belong to order, they belong to user, right?
   has_many :order_items
   has_many :items, through: :order_items
end

#app/models/order_item.rb
class OrderItem < ActiveRecord::Base
  #table name "order_items"
  #columns id | item_id | order_id | created_at | updated_at
  belongs_to :item
  belongs_to :order 
end

这是一个典型的has_many :through 关系，我相信你知道。

--

使用 Pavan 的更新答案；以上应该让您了解您可以从模型中获得的代码类型。