How to replace a hash key with another key

Question

I have a condition where, I get a hash

  hash = {\"_id\"=>\"4de7140772f8be03da000018\", .....}

and I want this hash as

Answer 1

rails Hash has standard method for it:

hash.transform_keys{ |key| key.to_s.upcase }

http://api.rubyonrails.org/classes/Hash.html#method-i-transform_keys

UPD: ruby 2.5 method