title: Make blank params[] nil
body: <p>When a user submits a form and leaves certain fields blank, they get saved as blank in the DB.  I would like to iterate through the params[:user] collection (for example) and if a field is blank, set it to nil before updating attributes.  I can't figure out how to do this though as the only way I know to iterate creates new objects:</p>
  
  <pre><code>coll = params[:user].each do |c|
      if c == ""
         c = nil
      end
  end
  </code></pre>
  
  <p>Thanks.</p>