Fix YAML loading on Ruby 3.1

[scudelletti]

Hello there!

I've noticed that this library is not working on ruby 3.1 and doing some debug I've found the following:
Ruby 3.1 uses psych 4.0.3 by default and this version doesn't support the deprecated way we call YAML.safe_load.

Before:

YAML.safe_load(ERB.new(File.read("config/database.yml")).result, [], [], true)

After:

YAML.safe_load(ERB.new(File.read("config/database.yml")).result, aliases: true)

This new psych version also allows us to use some of the its defaults when calling safe_load.

Method definition: https://github.com/ruby/psych/blob/e8d262fa108a1605443d7426c185452b538775be/lib/psych.rb#L323

Ruby 2.6.0 and up uses psych 3.1.0 which introduces this new method signature.

If we want to support old psych versions we will need create a conditional based on the gem version like it's done in this blog post.

Please let me know if changes are needed.

Thank you for your time and effort maintaining this library! 🙇 💐

[jhollinger]

Lost track of this over the holidays. Thanks for the patch, will be reviewing asap!

[jhollinger]

Given that the library support back to Ruby 2.1 and AR 4.2, I think supporting both older and newer Psych version would make sense. Would you mind adding that?

[scudelletti]

Given that the library support back to Ruby 2.1 and AR 4.2, I think supporting both older and newer Psych version would make sense. Would you mind adding that?

No problem at all. I'll look into it this week.
I'll let you know when I have the change ready for review.

[scudelletti]

@jhollinger I've updated the PR with support to old Psych versions so it should be ready for review.

[jhollinger]

I think lines 93 and 95 might be switched? I get this in Ruby 3.1:

test.rb

require 'yaml'
puts "Psych #{Psych::VERSION}"

erb_result = "foo: bar"
result = if Gem::Version.new(Psych::VERSION) >= Gem::Version.new('3.1.0.pre1')
  YAML.safe_load(erb_result, [], [], true)
else
  YAML.safe_load(erb_result, aliases: true)
end

[scudelletti]

I think lines 93 and 95 might be switched?

Good catch! IDK how I missed that! 🤦
It should be fixed now!