Difference between Ruby’s Hash and ActiveSupport’s HashWithIndifferentAccess

Question

What is the difference between Ruby’s Hash and ActiveSupport’s HashWithIndifferentAccess? Which is the best for dynamic hashes?

Answer 1

Below is the simple example that will show you difference between simple ruby hash & a "ActiveSupport::HashWithIndifferentAccess"

• HashWithIndifferentAccess allows us to access hash key as a symbol or string

Simple Ruby Hash

$ irb
  2.2.1 :001 > hash = {a: 1, b:2}
    => {:a=>1, :b=>2} 
  2.2.1 :002 > hash[:a]
    => 1 
  2.2.1 :003 > hash["a"]
    => nil 

ActiveSupport::HashWithIndifferentAccess

2.2.1 :006 >   hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1, b:2)
NameError: uninitialized constant ActiveSupport
    from (irb):6
    from /home/synerzip/.rvm/rubies/ruby-2.2.1/bin/irb:11:in `<main>'
2.2.1 :007 > require 'active_support/core_ext/hash/indifferent_access'
 => true 
2.2.1 :008 > hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1, b:2)
 => {"a"=>1, "b"=>2} 
2.2.1 :009 > hash[:a]
 => 1 
2.2.1 :010 > hash["a"]
 => 1 

• class HashWithIndifferentAccess is inherited from ruby "Hash" & above special behavior is added in it.