How to: Track Additional Data
```ruby
class Ahoy::Store < Ahoy::DatabaseStore
  def track_visit(data)
    data[:accept_language] = request.headers["Accept-Language"]
    super(data)
  end
end
```

Two useful methods you can use are `request` and `controller`.

You can pass additional visit data from JavaScript with:

```javascript
ahoy.configure({visitParams: {referral_code: 123}});
```

And use:

```ruby
class Ahoy::Store < Ahoy::DatabaseStore
  def track_visit(data)
    data[:referral_code] = request.parameters[:referral_code]
    super(data)
  end
end
```