不要在块中以这种方式定义常量。在块中定义 class 时

Question

我正在路由块中定义一个 class 来处理 ajax 东西

#config/routes.rb
Rails.application.routes.draw do
  class OnlyAjaxRequest
     def matches?(request)
       request.xhr?
     end
  end
#rest of the routes
end

但是我在编辑器中收到此警告：

Do not define constants this way within a block.Lint/ConstantDefinitionInBlock(RuboCop)

这似乎是一种不好的做法，但我不确定如何解决它，有什么想法吗？

Answer 1

来自docs：

Do not define constants within a block, since the block’s scope does not isolate or namespace the constant in any way.

If you are trying to define that constant once, define it outside of the block instead, or use a variable or method if defining the constant in the outer scope would be problematic.

您可以在块外定义 OnlyAjaxRequest class 来解决问题。

class OnlyAjaxRequest
  def matches?(request)
    request.xhr?
  end
end

Rails.application.routes.draw do
  # ...
end

由于约束非常简单，您甚至不需要创建 class。您可以将 lambda 传递给 constraints 选项。

is_ajax_request = ->(request) { request.xhr? }

get '/some_route', to: 'test#action', constraints: is_ajax_request

Answer 2

我不明白你为什么要在你的具体案例中的块内定义一个 class，因为你可以同样很好地定义它，但万一你遇到了你真的想在本地做，你可以做

 Object.const_set(
   "OnlyAjayRequest", 
     Class.new { 
       def matches?(request) 
         request.xhr?
       end 
     }
 )

不要在块中以这种方式定义常量。在块中定义 class 时

Do not define constants this way within a block. When defining class within a block

ruby

ruby-on-rails

rubocop