Ruby: merge nested hash

Question

I would like to merge a nested hash.

a = {:book=>
    [{:title=>\"Hamlet\",
      :author=>\"William Shakespeare\"
      }]}

b = {:book=>
    [{         


        

Answer 1

I think Jon M's answer is the best, but it fails when you merge in a hash with a nil/undefined value. This update solves the issue:

class ::Hash
    def deep_merge(second)
        merger = proc { |key, v1, v2| Hash === v1 && Hash === v2 ? v1.merge(v2, &merger) : [:undefined, nil, :nil].include?(v2) ? v1 : v2 }
        self.merge(second, &merger)
    end
end

a.deep_merge(b)