Sandip Mane
by Sandip Mane
1 min read


  • Ruby
  • Ruby on Rails


  • class
  • ruby

When I found out how the params could be accessed using both symbol and string as keys, I dived deep to figure out about ActiveSupport::HashWithIndifferentAccess class in Rails.

In this blog, we will go through it’s implemention. Check the Source Code and Documentation.

> rgb =
> rgb[:black] = '#000000'
> rgb[:black]  # => '#000000'
> rgb['black'] # => '#000000'

So, this is what it is, we can use both symbols and strings as keys to access the Hash.

Then, in what type the keys are actually stored?

> rgb.keys    # => ["black"]

Strings! Let’s see how its done.


Above, we have a method which is used to add a key value pair to the hash. We can see that the key and value are being converted before storing. regular_writer is just an alias for []=.

Here are the methods which are used to convert key and value.

As we can see, the key is converted to string from symbol and a new object of the same class is created when the value is hash.

Similarly, when we merge! another hash into this hash, the keys and values are converted before its merged.


When all the keys are strings, how can it be accessed using symbols?

That’s it, the given symbol is converted to string as well!


In this post (for beginners), we saw how ActiveSupport::HashWithIndifferentAccess class adds magical methods to ruby’s Hash class.

And as always, thanks for reading!😃