Classes for attributes validation

Question

I have two classes responsible for attributes validation:

class NameValidator < ActiveModel::EachValidator
 def validate_each(record, attribute, value)
 message = options.fetch(:message, I18n.t('errors.attributes.name.invalid'))
 record.errors[attribute] << message unless NameValidator.valid_name?(value)
 end
 def self.valid_name?(name)
 name =~ /\A[a-z][\w\p{Blank}]+\z/i
 end
end

and the second one:

class EmailValidator < ActiveModel::EachValidator
 def validate_each(record, attribute, value)
 message = options.fetch(:message, I18n.t('errors.attributes.email.invalid'))
 record.errors[attribute] << message unless EmailValidator.valid_email?(value)
 end
 def self.valid_email?(email)
 email =~ /\A.+@.+\..+\z/i
 end
end

They're basically the same. Should I inherit them from one class with protected utility methods or what?

• 200_success: Can you show how you're using these validators? Couldn't you use validates_format_of instead?

Answer 1

By creating a base class and then inheriting from it, you end up with no duplication and with an architecture that can be easily extended.

I don't think that you should bother having valid? as protected. Calling valid? from outside is a common use case and doesn't violate encapsulation.

class Validator < ActiveModel::EachValidator
 def validate_each(record, attribute, value)
 message = options.fetch(:message, I18n.t('errors.attributes.name.invalid'))
 record.errors[attribute] << message unless self.valid?(value)
 end
 def self.valid?(value)
 raise NotImplementedError
 end
end
class NameValidator < Validator
 def self.valid?(value)
 value =~ /\A[a-z][\w\p{Blank}]+\z/i
 end
end
class EmailValidator < Validator
 def self.valid?(value)
 value =~ /\A.+@.+\..+\z/i
 end
end

• SirPython: Welcome to Code Review! Good job on your first answer
• Thomas Andrews: The other reason to keep valid? public is that you can unit test it.