title: Making changes to Objects in a rails migration
body: <p>I'd like to migrate a belongs_to relationship that I currently have to a has_and_belongs_to_many relationship. Ideally I'd like to do this in the migration that I've built.</p>
  
  <p>When I add this new migration which is the join IDs for these two items, can I then afterwards make changes to the model in that Migration?</p>
  
  <pre><code>#migration code goes here to add the new item field
  Item.find(:all).each do |item|
  specific changes to item to account for the new relationship
  end
  </code></pre>
  
  <p>Or is that not something I can do within that rake environment? I'd like to migrate the objects over to using the new HABTM system, will I have to check for that in the actual code itself and run that as a separate rake task before launching the instance of the application?</p>