Issue #11643 has been updated by Gabe Kopley.


Matthew Kerwin wrote:
> How about:
> 
>     params.?[:order].?[shipping_info].?[country]

Thanks Matthew, I'll be honest, I hadn't thought of that. There is a certain appeal in avoiding adding a new method on Hash. On the other hand, by adding a new method we can more easily and more beautifully do metaprogramming, use a potentially more concise expression, convey more rich semantics, and possibly reduce the number of method calls.

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Feature #11643: A new method on Hash to grab values out of nested hashes, failing gracefully
https://bugs.ruby-lang.org/issues/11643#change-54672

* Author: Gabe Kopley
* Status: Open
* Priority: Normal
* Assignee: 
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(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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