Store Item public_id as int rather than string

db/migrate/20120814211443_public_i_d_as_int.rb

@@ -0,0 +1,19 @@
+class PublicIDAsInt < ActiveRecord::Migration
+  def up
+    execute <<-EOSQL
+    ALTER TABLE items
+      ALTER COLUMN public_id
+      TYPE int
+      USING public_id::int
+    EOSQL
+  end
+
+  def down
+    execute <<-EOSQL
+    ALTER TABLE items
+      ALTER COLUMN public_id
+      TYPE text
+      USING public_id::char
+    EOSQL
+  end
+end