Refactor controllers

app/controllers/playlists_controller.rb

@@ -1,4 +1,6 @@
 class PlaylistsController < ApplicationController
+  before_filter :set_playlist, only: %i[edit update]
+
   def index
     @playlists = Playlist.all
   end
@@ -11,29 +13,30 @@ class PlaylistsController < ApplicationController
     @playlist = current_user.playlists.build playlist_params
 
     if @playlist.save
-      redirect_to action: 'index'
+      redirect_to action: :index
     else
-      render action: 'new'
+      render :new
     end
   end
 
   def edit
-    @playlist = Playlist.find(params[:id])
   end
 
   def update
-    @playlist = Playlist.find(params[:id])
-
     if @playlist.update_attributes playlist_params
-      redirect_to action: 'index'
+      redirect_to action: :index
     else
-      render action: 'edit'
+      render :edit
     end
   end
 
 
   private
 
+  def set_playlist
+    @playlist = Playlist.find(params[:id])
+  end
+
   def playlist_params
     params.require(:playlist).permit :name
   end