How to use Sequel::Plugins::JsonSerializer#to_json method when aggregation function is used

Question

There is a model Game like this. The Game has date and point columns.

class Game < Sequel::Model
  plugin :json_serializer
end

When I use a aggregation function it returns a error.

Game.select(Sequel.lit('max(point) as max_point')).group(:date).to_json
#=>`NoMethodError: undefined method `max_point'`

I can avoid the error by defining a method max_point in Game model.

def max_point
  @values[:max_point]
end

I don't want to define a new method every time when I use a aggregation function. Is there a recommended way to solve the problem like this?