[Proposal] A new cop to prefer fetch for Rails.application.secrets

[gfx]

Rails.application.secrets.foo returns nil if the entry does not exist. However, accessing a missing entry is likely to a typo.

Fortunately, it has fetch() method that raises errors in a missing entry, so it's a good idea to prefer fetch() instead of the use of getter.

e.g.

# good
foo = Rails.application.secrets.fetch(:foo)

# bad
foo = Rails.application.secrets.foo

[mikegee]

Good idea. Let's include Rails.application.credentials too, since Rails 5.2 replaces the secrets stuff with credentials.

[koic]

I think that a bang method should be used instead of fetch method because the Rails Guides shows a bang method.
https://guides.rubyonrails.org/security.html#custom-credentials

Rails.application.secrets has the same behavior.

% bin/rails c
Loading development environment (Rails 5.2.3)
[1] pry(main)> Rails.application.credentials.some_api_key
=> nil
[2] pry(main)> Rails.application.credentials.some_api_key!
KeyError: :some_api_key is blank
from /Users/koic/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/ordered_options.rb:49:in `method_missing'
[3] pry(main)> Rails.application.secrets.some_api_key
=> nil
[4] pry(main)> Rails.application.secrets.some_api_key!
KeyError: :some_api_key is blank
from /Users/koic/.rbenv/versions/2.6.3/lib/ruby/gems/2.6.0/gems/activesupport-5.2.3/lib/active_support/ordered_options.rb:49:in `method_missing'

No bang method is not a deprecation. If no bang is deprecated or a strongly recommended document (e.g. Rails Guides) with bang is accepted by Rails team (rails/rails repo), I think it is worthwhile to make cop with bang method a good case.

[mikegee]

Thanks @koic! I didn’t know about that.

[tejasbubane]

If no bang is deprecated or a strongly recommended document (e.g. Rails Guides) with bang is accepted by Rails team (rails/rails repo), I think it is worthwhile to make cop with bang method a good case.

I think it is worthwhile regardless to make a cop that suggests some form of better way to access credentials than direct access.