allow ActiveRecord::Core#slice to use array arg

[Cohen-Carlisle]

Summary

This allows ActiveRecord::Core#slice to take an array of attributes to retain in addition to a splat of arguments, making it behave like like ActiveRecord::QueryMethods#select.

Other Information

Imagine you have some code as follows:

class User < ApplicationRecord
  PUBLIC_FIELDS = %i(foo bar baz).freeze

  scope :public_fooed, -> { select(PUBLIC_FIELDS).where(foo: true) }

  def publicize
   slice(*PUBLIC_FIELDS)
  end
end

It annoys me that to filter attributes at the model class level (while doing a ::select), you don't need to splat PUBLIC_FIELDS, but you do when doing it at the model object level (with #slice).

Since ActiveRecord::Core#slice will never have attributes (or methods) that are arrays, we can safely flatten its arguments to make it behave like ::select with regard to array arguments.

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[rafaelfranca]

Could you add a test case?

[Cohen-Carlisle]

@rafaelfranca sure thing, let me know if 9f9b999 will suffice

[rafaelfranca]

Only a small comment. After you fix it could you add a CHANGELOG entry and squash your commits? Thanks.

[rafaelfranca]

it is the other way around. assert_equal attrs, topic.slice(attrs.keys)

[Cohen-Carlisle]

@rafaelfranca done and done

[Cohen-Carlisle]

Checking in on this PR.

[prathamesh-sonpatki]

Can you add a fullstop at the end.

[Cohen-Carlisle]

@prathamesh-sonpatki Done and rebased/squashed.

[prathamesh-sonpatki]

Looks good, let's wait for the committer now 😄

[guilleiguaran]

thank you very much for this, I've missed having this in some occasions