title: Rails 3, add radio button with migration, how set a default to existing data?
body: <p>We used a migration to add a new field to our Posts table called new_choice:integer with :default => 1</p>
  
  <p>On the edit form we made it a radio button with 3 choices A,B,C represented by values 1,2,3</p>
  
  <p>When a NEW record is created, the "A" button will be selected by default.</p>
  
  <p>However, when an already-existing record is edited, the current value is nil so NO radio button is selected.</p>
  
  <p>Is there a way to have the erb form check a particular button (A/1) if the field value sis not the "valid" choices of 1,2,3?</p>