How can I use Ruby's to_json in a subclass and include super's json? -

#!/usr/bin/env ruby  require 'json'  class   def to_json(*a)     { :a => 'a' }.to_json(*a)   end end  class b <   def to_json(*a)     super({ :b => 'b' })   end end  puts b.new.to_json 

produces

{"a":"a"} 

how produce

{"a":"a", "b":"b"} 

in reasonable way?

i'm using ruby 1.9.3 , latest json gem.

a related question is: arguments *a to_json? i've scoured docs no avail.

you have 2 hashes {:a=>'a'} , {:b=>'b'} in 2 classes, they're encapsulated i.e. hidden outside world. way can see parse json string hash , merge them, convert result json.

class b <   def to_json(*a)     json.parse(super).merge({:b=>'b'}).to_json   end end 

but here small difference: you're merging {:a=>'a',:b=>'b'} , got {"a":"a","b":"b"}

*a parameter set options json format