Display comments count

app/models/comment.rb

@@ -5,7 +5,7 @@ class Comment < ActiveRecord::Base
   validates :user_id, :presence => true
 
   belongs_to :user
-  belongs_to :asciicast
+  belongs_to :asciicast, :counter_cache => true
 
   attr_accessible :body
 

app/views/asciicasts/_preview.html.erb

@@ -19,4 +19,8 @@
   <% if asciicast.description.present? %>
     <p class="description"><%= asciicast.description %></p>
   <% end %>
+
+  <% if asciicast.comments_count > 0 %>
+    <p><%= link_to "#{asciicast.comments_count} comments", asciicast_path(asciicast, :anchor => 'comments') %></p>
+  <% end %>
 </li>

db/migrate/20120409142151_add_comments_count_to_asciicast.rb

@@ -0,0 +1,5 @@
+class AddCommentsCountToAsciicast < ActiveRecord::Migration
+  def change
+    add_column :asciicasts, :comments_count, :integer, :null => false, :default => 0
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20120406152447) do
+ActiveRecord::Schema.define(:version => 20120409142151) do
 
   create_table "asciicasts", :force => true do |t|
     t.integer  "user_id"
@@ -35,6 +35,7 @@ ActiveRecord::Schema.define(:version => 20120406152447) do
     t.boolean  "featured",         :default => false
     t.string   "username"
     t.text     "snapshot"
+    t.integer  "comments_count",   :default => 0,     :null => false
   end
 
   add_index "asciicasts", ["created_at"], :name => "index_asciicasts_on_created_at"