store rendered notes of todos in database to avoid costly rendering when you load a page

db/migrate/20120412072508_add_rendered_notes.rb

@@ -0,0 +1,26 @@
+class AddRenderedNotes < ActiveRecord::Migration
+  def self.up
+    add_column :todos, 'rendered_notes', :text
+    
+    puts "-- Clearing show_from dates from completed todos"
+    # clear up completed todos that have show_from set. These could have been left over from before the AASM migration
+    Todo.completed.find(:all, :conditions =>[ "NOT(show_from IS NULL)"]).each {|t| t.show_from=nil; t.save!}
+    puts "-- Generating new column values from notes. This may take a while."
+    # Call save! on each todo to force generation of rendered_todos
+    i=0; max = Todo.all.count; start = Time.now
+    Todo.all.each do |todo|
+      todo.save(false)
+      i = i + 1
+      if i%250==0
+        elapsed_sec = (Time.now-start)
+        remaining = (elapsed_sec / i)*(max-i)
+        puts "Progress: #{i} / #{max} (#{(i.to_f/max.to_f*100.0).floor}%) ETA=#{remaining.floor}s"
+      end
+    end
+    puts "Done: #{i} / #{max}"
+  end
+
+  def self.down
+    remove_column :todos, 'rendered_notes'
+  end
+end