The scope of custom helper

I have defined my helper function in Helper:

module CarsHelper

  def my_helper
    ...
  end

end

But I can neither used it(my_helper) in my CarsController nor in Car model, is it so t开发者_JAVA百科hat the custom helper can only be used in View?

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Helpers are normally for views. But you can include them in your controllers as well. Just add

helper :cars

to your controller. (docs)

Models are out of scope for helpers. Use class or instance methods in there instead.

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The new way to use view helpers in controllers is to use: helpers.[helpername]

See this for more.