Ruby-on-rails 包含模块时出现“未初始化的常量”错误
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"Uninitialized constant" error when including a module
提问by Coderama
I am trying to reference an association extension but it errors with:
我正在尝试引用关联扩展，但它出现以下错误：
NameError (uninitialized constant User::ListerExtension):
app/models/user.rb:2:in `<class:User>'
Here is my implementation:
这是我的实现：
app/models/user.rb
应用程序/模型/user.rb
class User < ActiveRecord::Base
include ListerExtension
has_and_belongs_to_many :roles, :uniq => true, :extend => Lister
lib/lister.rb
库/lister.rb
module ListerExtension
def lister
self.map(&:to_s).join(', ')
end
end
I am using Rails v3.1.3.
我正在使用 Rails v3.1.3。
回答by Xavier Holt
Andrew Marshall has an excellent point about the auto-load setup (see the question he links for more on that), but also: Because you named your class ListerExtension, Rails will be looking for a file named lister_extension.rb- notlister.rb. It's smart, but it's not that smart.
安德鲁·马歇尔对自动加载设置一个很好的点（看他的条链路上的问题），也：因为你命名你的类ListerExtension，Rails会寻找一个文件名为lister_extension.rb-不是lister.rb。它很聪明，但它并不那么聪明。
Hope that helps!
希望有帮助！
