The problem with `hash.fetch_in(:order, :shipping_info, :country, 'Not found')` is that `'Not found'` is a (possibly) valid key. You would need to implement this with a kwarg.

```ruby
class Hash
  def fetch_in(*keys, **kwargs, &block)
    keys = keys.dup
    ckey = keys.shift

    unless self.key?(ckey)
      return kwargs[:default] if kwargs.key?(:default)
      return block.call(ckey) if block
      fail KeyError, "key not found #{ckey.inspect}"
    end

    child = self[ckey]

    if keys.empty?
      child
    elsif child.respond_to?(:fetch_in)
      child.fetch_in(*keys, **kwargs, &block)
    else
      fail ArgumentError, 'more keys than Hashes'
    end
  end
end

a = {
  a: {
    b: {
      c: :d
    }
  }
}

def y
  yield
rescue => e
  e
end

p y { a }
p y { a.fetch_in(:a) }
p y { a.fetch_in(:a, :b) }
p y { a.fetch_in(:a, :b, :c) }
p y { a.fetch_in(:a, :b, :c, :d) }
p y { a.fetch_in(:a, :b, :d) }
p y { a.fetch_in(:a, :b, :d, default: 'z') }
p y { a.fetch_in(:a, :b, :d) { 'z' } }
```

As a proposed name, I suggest `locate`.

On Tue, Nov 3, 2015 at 7:03 PM, <dsisnero@gmail.com> wrote:
Issue #11643 has been updated by Dominic Sisneros.


Yukihiro Matsumoto wrote:
> I prefer method way to (already reverted) `params.?[:order].?[:shipping_info].?[:country]`.
> I am not sure `dig` is the best name for it. It's short, concise thought.
> Any other idea, anyone?
>
> Matz.

clojure has get-in for their maps, how about fetch_in with replacement like fetch

hash.fetch_in(:order, :shipping_info, :country, 'Not found')


----------------------------------------
Feature #11643: A new method on Hash to grab values out of nested hashes, failing gracefully
https://bugs.ruby-lang.org/issues/11643#change-54698

* Author: Gabe Kopley
* Status: Open
* Priority: Normal
* Assignee:
----------------------------------------
(I posted this to the mailing list last year [0] and received no response, but am inspired to file an issue here based on the positive reception to https://bugs.ruby-lang.org/issues/11537 )

This comes up sometimes in Rails programming [1]:

`params[:order] && params[:order][:shipping_info] && params[:order][:shipping_info][:country]`

or

`params[:order][:shipping_info][:country] rescue nil`

or

`params.fetch(:order, {}).fetch(:shipping_info, {}).fetch(:country, nil)`

What if Hash gave us a method to accomplish this more concisely and semantically?

Eg.

`params.traverse_nested_hashes_and_return_nil_if_a_key_isnt_found(:order, :shipping_info, :country)`

Or to take a nice method name suggestion [2]:

`params.dig(:order, :shipping_info, :country)`

Another example solution is https://github.com/intridea/hashie#deepfetch (Although I don't like "fetch" in this method name since it doesn't and can't take a default value as an argument like Hash#fetch does)

What do you all think?


[0] https://groups.google.com/forum/#!topic/ruby-core-google/guleNgEJWcM

[1]
https://groups.google.com/d/msg/rubyonrails-core/bOkvcvS3t_A/QXLEXwt9ivAJ
https://stackoverflow.com/questions/1820451/ruby-style-how-to-check-whether-a-nested-hash-element-exists
https://stackoverflow.com/questions/19115838/how-do-i-use-the-fetch-method-for-nested-hash
https://stackoverflow.com/questions/10130726/ruby-access-multidimensional-hash-and-avoid-access-nil-object

[2] http://stackoverflow.com/a/1820492/283398



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