lock issues

gistfile1.rb

def update
  @text_frame = TextFrame.find(params[:id])
  
  # lock already exists, so this will return the existing lock
  lock = Lock.new(current_user, @text_frame, "text_frame", params[:text_frame][:last_modified])
  
  if (!lock.save)
    # handle error here, send bad status code and message
  end
  
  @text_frame.update_attributes(params[:text_frame])
  
  lock.destroy # now we've destroyed the lock that we didn't create and was supposed to be left
  
  respond_with @text_frame
end