How to use BigDecimal.as_json to format the sum of BigDecimal "1.20" not in "1.2", but in "1.20"?

Question

Ruby on Rails

When an object instance is serialized using .as_json, one of the attributes of type BigDecimal(8,2) is serialized without zero, i.e. So:

> BigDecimal.new("1.20").as_json
=> "1.2"

Those. there is no final digit 0 in the price.
Trial code on the Struct example:

Price = Struct.new(:product, :money)
obj = Price.new 'квас', BigDecimal.new("1.20")
puts obj.to_json

=> {"product":"kvass","money":"1.2"}
How can I override BigDecimal.as_json so that the amount is formatted as nnn.nn?
I need to format it like this:
'%.2f' % BigDecimal.new("1.20")
Only I need to override it locally, within the same ActiveRecord model, not globally.
Rails 4.2, Ruby 2.3, gem json 1.8.3

Answer 1

Something I did not immediately guess about such a simple solution:

h = my_model.as_json
h[:price] = '%.2f' % my_model.price  # переопределяем результат BigDecimal.as_json с новым форматированием строки