hit.rb

class Hit < ActiveRecord::Base
  
  belongs_to :user
  belongs_to :shot, :counter_cash => true
  
  validate_on_create :check_for_gaming
  
  def request=(request)
    self.user_ip    = request.remote_ip
    self.user_agent = request.env['HTTP_USER_AGENT']
  end
  
  private
  
  def check_for_gaming
    # smart method that checks for shit
  end
  
end

hits.rb

class Hits < Application
  
  # this is a nested resource with only a create method
  # we use render_then_call (merb only) just to pass back
  # a 200 status before doing the calculation
  # this action is hit with a XHR POST that looks like...
  # http://example.com/shot/4587/hit
  #
  def create
    only_provides :js
    
    # returns a 200 and moves on. (if rails omit the render)
    Merb.render_then_call(:status => 200) do
      @shot = @shot.find(params[:shot_id])
      @hit = Hit.new(:shot => @shot, :user_id => current_user) #will pass in nil if user is not logged in
      @hit.request = request
      @hit.save
    end
  end
  
end