rails controller with ivar set in private method

gistfile1.rb

class HistoryController < ApplicationController
  before_filter :get_history, only: [:show, :edit, :update, :destroy]

  def index
    @histories = History.all
  end

  def show
    @history = History.find(params[:id])
  end

  def new
    @history = current_user.cosplay_histories.new
  end

  def edit

  end

  def create
    @history = current_user.cosplay_histories.new(params[:history])

    respond_to do |format|
      if @history.save
        format.html { redirect_to @history, notice: 'History was successfully created.' }
        format.json { render json: @history, status: :created, location: @history }
      else
        format.html { render action: "new" }
        format.json { render json: @history.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    respond_to do |format|
      if @history.update_attributes(params[:history])
        format.html { redirect_to @history, notice: 'History was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @history.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @history.destroy

    respond_to do |format|
      format.html { redirect_to histories_url }
      format.json { head :no_content }
    end
  end
  
  private

  def get_history
    @history = History.find(params[:id])
  end
end