ticket.rb

require 'activesupport/json_encoder'

class A
  def initialize; @thing = "zoidberg"; end
      
  def as_json(options={})
    {
      :whynot => @thing,
      :this => "string"
    }
  end
end

class B
  def initialize; @obja = A.new; end
  
  def as_json(options={})
    {
      :obja => @obja
    }
  end
end

# Works
puts B.new.to_json

# Doesn't work
puts JSON.pretty_generate(B.new)