Ruby - Convert nested objects to json?

Question

How to convert nested objects to json in ruby?
For example, an object obj contains a custom instance variable b
If you use to_json, the content of b cannot be output.
What is needed is the output of obj.to_s, but if it is in the form of json
It is possible to use to_yaml, but I hope to convert it directly to json

By the way, to_json and to_yaml are obviously the same function. Why is there such a difference in results?

Answer 1

require 'oj'

class A
    def initialize a=[1,2,3], b='hello'
        @a = a
        @b = b
    end
end

puts Oj::dump a, :indent => 2, :mode => :compat

Output:

{
  "a":[
    1,
    2,
    3
  ],
  "b":"hello"
}