Rails: uninitialized constant methodtypecontroller

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Ruby

Rails

I just started my rails. I try to set routes but my controller format has an underline. Therefore I do not how to write route.

What I have tried:

This is my controller file name:
method_types_controller.rb

This is what I have tried on my route:

Rails.application.routes.draw do

  # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
  get 'method_type/index'
  root 'method_type#index'

end

The result shows incorrectly:
routing error
uninitalized constant MethodTypeController