somefile.rb

class TutorsController < ApplicationController
  before_action :authenticate_user!
  
  respond_to :html
  
  def new
    @tutor = current_user.build_tutor
    respond_with @tutor
  end

  def show
    @tutor = current_user.tutor
    respond_with @tutor
  end
  
  def create
    @tutor = current_user.build_tutor(tutor_params)
    
    respond_with(@tutor) do |format|
      if @tutor.save
        flash[:success] = 'Tutor profile created!'
      else
        flash[:error] = 'Tutor profile not created'
      end
    end
  end
  
  def update
    @tutor = current_user.tutor
    
    respond_with(@tutor) do |format|
      if @tutor.update_attributes(tutor_params)
        flash[:success] = 'Tutor profile updated'
      else
        flash[:error] = 'Tutor profile not updated'
      end
    end
  end
  
  private
    def tutor_params
      params.require(:tutor).permit(:id, :description, :rate, :country)
    end
end

class Tutor < ActiveRecord::Base
  belongs_to :user
end

class User < ActiveRecord::Base
  has_one :tutor, autobuild: true, dependent: :destroy
  
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable
end