Rails core - Nov 2014 - Add ActionController::Parameters#dig to grab values out of nested params, failing gracefully

Hi folks,

For better or worse, this is a pattern you see pretty often in real-world 
Rails code [0]:

  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 we had a method to accomplish this more concisely?

Eg.

  params.traverse_nested_params_and_return_nil_if_a_key_isnt_found(:order, 
:shipping_info, :country)

Or to take a nice method name suggestion [1]:

  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)

Would a method like this possibly belong in ActionController::Parameters? 
Or maybe even in Active Support extensions on Hash (gasp!)? Or is it just 
an all-around terrible idea?

Thanks,
Gabe

[0] Sources:
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

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

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