How do I use the fetch method for nested hash?

Question

I have the following hash:

hash = {'name' => { 'Mike' => { 'age' => 10, 'gender' => 'm' } } }

I can access the age by:

hash['name']['Mike']['age']

What if I used Hash#fetch method? How can I retrieve a key from a nested hash?

As Sergio mentioned, the way to do it (without creating something for myself) would be by a chain of fetch methods:

hash.fetch('name').fetch('Mike').fetch('age')

Answer 1

EDIT: there is a built-in way now, see this answer.

---

There is no built-in method that I know of. I have this in my current project

class Hash
  def fetch_path(*parts)
    parts.reduce(self) do |memo, key|
      memo[key.to_s] if memo
    end
  end
end

# usage
hash.fetch_path('name', 'Mike', 'age')

You can easily modify it to use #fetch instead of #[] (if you so wish).