Existence of ActiveModel::SecurePassword authenticate method (Rails 6) - ruby-on-rails

Question

The "authenticate" method can only be found here: https://apidock.com/rails/ActiveModel/SecurePassword/InstanceMethodsOnActivation/authenticate
, with version 6.0.0 being grayed out. So this seems to be outdated.
I have searched the Rails 6 documentation for the authenticate method, and found no record of it under https://api.rubyonrails.org/classes/ActiveModel/SecurePassword/ClassMethods.html.
Yet in the code snippet on the same page
# Schema: User(name:string, password_digest:string, recovery_password_digest:string)
class User < ActiveRecord::Base
has_secure_password
has_secure_password :recovery_password, validations: false
end
user = User.new(name: 'david', password: '', password_confirmation: 'nomatch')
user.save # => false, password required
user.password = 'mUc3m00RsqyRe'
user.save # => false, confirmation doesn't match
user.password_confirmation = 'mUc3m00RsqyRe'
user.save # => true
user.recovery_password = "42password"
user.recovery_password_digest # => "$2a$04$iOfhwahFymCs5weB3BNH/uXkTG65HR.qpW.bNhEjFP3ftli3o5DQC"
user.save # => true
user.authenticate('notright') # => false
user.authenticate('mUc3m00RsqyRe') # => user
user.authenticate_recovery_password('42password') # => user
User.find_by(name: 'david')&.authenticate('notright') # => false
User.find_by(name: 'david')&.authenticate('mUc3m00RsqyRe') # => user
The authenticate method is still used (user.authenticate). Where does this method come from if I can't find it in the latest documentation?
Edit:
A related question regarding differences in documentation: I am able to find ActionDispatch::Request::Session on rubydocs but not on api.rubyonrails.
https://www.rubydoc.info/docs/rails/ActionDispatch/Request/Session
https://api.rubyonrails.org/classes/ActionDispatch/Request.html
Now I am not certain where I should be looking when searching for methods. Is api.rubyonrails not the "definitive" place to look for documentation?

Answer 1

It looks like they forgot to mention it in the documentation for has_secure_password. If you look into source code of ActiveModel::SecurePassword. You will find
# Returns +self+ if the password is correct, otherwise +false+.
#
# class User < ActiveRecord::Base
# has_secure_password validations: false
# end
#
# user = User.new(name: 'david', password: 'mUc3m00RsqyRe')
# user.save
# user.authenticate_password('notright') # => false
# user.authenticate_password('mUc3m00RsqyRe') # => user
define_method("authenticate_#{attribute}") do |unencrypted_password|
attribute_digest = public_send("#{attribute}_digest")
BCrypt::Password.new(attribute_digest).is_password?(unencrypted_password) && self
end
alias_method :authenticate, :authenticate_password if attribute == :password
You can se it is now defined as dynamic method based on the parametr name provided to has_secure_password method. So they implemented it in more general way. And to be more friendly with backwards compatibility the implemented the alias authenticate for authenticate_password which was the original implementation.
Unfortunately these dynamic methods are not very well documented in the rails API docs.