How to iterate over deep nested hash without known depth in Ruby - ruby-on-rails

Question

I have multiple YAML (localization) files. I parse them and convert to hash in Ruby.
For example this is one of them:
hello: Hallo
messages:
alerts:
yay: Da!
no: Nein
deep:
nested:
another:
level:
hi: Hi!
test: Test!
Basically, this is look like a locale file in Rails App using YAML.
What I want to do is iterate this Hash recursively and get key and value. So that i can translate values one-by-one from API Endpoint like Google Translate. I want to keep nested hashes in same schema so that Rails can find by keys.
I know i can use nested loops but there is no guarantee that nested hashes is a known number of. How can I iterate this hash recursively so i can manipulate values (translate/replace)?
Expected Result: (after used translation service from API call)
hello: Hello
messages:
alerts:
yay: Yup!
no: No
deep:
nested:
another:
level:
hi: Hi!
test: Test!
What I've tried so far:
hash = YAML.load('de.yml') # parse source Deutsch locale
new_hash = {}
hash.each |key, value| do
new_hash[key] = translate_func(value) # here... translate value then assign very same key including parents.
# Do more loops....
end
# Now write this new_hash to yaml file...
But this only manipulate hello only. To get work with others I have to make a loop. But how many keys are nested is unknown.
How can I iterate over all values of locale hash and keep the schema intact?
And if possible but not mandatory, I would be very happy if we can keep the order of keys on final result. That would be awesome to find missing keys later when manually reviewed.
I am very new to ruby.
I am using Ruby 2.7.2
Conclusion / Resolve
All answers are correct and I love all of them. However, I would like to be able to control both keys and values. Not just transform by values. Therefore, I accepted an answer that fits to my needs. I was able to do my intention with selected answer.

Answer 1

You can use deep_transform_values! on your hash object to change the values recursively. (Or its non-destructive version deep_transform_values which returns a new hash instead of changing the original hash.)
hash.deep_transform_values! { |value| translate_func(value) }
Note: deep_transform_values! is a Rails method. See the source code here for inspiration if you're not using Rails.

Answer 2

If you want a simple non-rails solution then you can just create a recursive method:
def recurse(hash)
hash.transform_values do |v|
case v
when String
v.reverse # Just for the sake of the example
when Hash
recurse(v)
else
v
end
end
end
Output:
{"hello"=>"ollaH", "messages"=>{"alerts"=>{"yay"=>"!aD", false=>"nieN"}, "deep"=>{"nested"=>{"another"=>{"level"=>{"hi"=>"!iH"}}}}}, "test"=>"!tseT"}
However this might be a case of reinventing the wheel - you can use the i18n gem for translations and i18n-tasks to prefill your YAML files with translations from the Google Translate API.

Answer 3

So, you want to parse recursively until there are no more levels to parse into.
It’s super common in software and referred to as “recursion”. Have a search around to learn more about it - it’ll come up again and again in your journey. Welcome to ruby btw!
As for your actual current problem. Have a read of https://mrxpalmeiras.wordpress.com/2017/03/30/how-to-parse-a-nested-yaml-config-file-in-python-and-ruby/
But also, consider the i18n gem. See this answer https://stackoverflow.com/a/51216931/1777331 and the docs for the gem https://github.com/ruby-i18n/i18n This might fix your problem of handling internationalisation without you having to get into the details of handling yaml files.