Dynamic-Attributes.md

@@ -7,8 +7,11 @@ This method allows defining a conditional value that, if present in the result s
 In any model, you just need to call `dynamic_attribute` method, passing an name for it and the block that will be called in case the attribute is not present.
 
 ```ruby
-dynamic_attribute(:last_comment) do
-  comments.order(id: :desc).first.content
+# models/user.rb
+class User < ActiveRecord::Base
+  dynamic_attribute(:last_comment) do
+    comments.order(id: :desc).first.content
+  end
 end
 ```