You can easily list given model validators by calling validators method on the class name:

User.validators # => array of validators

If you define presence validator on your User model:

class User < ActiveRecord::Base
  validates :email, presence: true
end

you can access validator attributes the following way:

email_presence_validator = User.validators.first
email_presence_validator.class # => ActiveRecord::Validations::PresenceValidator
email_presence_validator.attributes # => [:email]
email_presence_validator.options # => {}

The options method returns options like :if or :unless conditions that are passed to the validator definition as extra arguments. Experiment with other types of validations to see how it's working.

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