Refactor controllers

app/controllers/tracks_controller.rb

@@ -1,10 +1,11 @@
 class TracksController < ApplicationController
+  before_filter :set_track, only: %i[show edit update]
+
   def index
     @tracks = Track.all
   end
 
   def show
-    @track = Track.find(params[:id])
   end
 
   def new
@@ -12,7 +13,6 @@ class TracksController < ApplicationController
   end
 
   def edit
-    @track = Track.find(params[:id])
   end
 
   def create
@@ -26,8 +26,6 @@ class TracksController < ApplicationController
   end
 
   def update
-    @track = Track.find(params[:id])
-
     if @track.update_attributes track_params
       redirect_to action: :index
     else
@@ -38,6 +36,10 @@ class TracksController < ApplicationController
 
   private
 
+  def set_track
+    @track = Track.find(params[:id])
+  end
+
   def track_params
     params.require(:track).permit %i[name file]
   end