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?

Can you show how you're using these validators? Couldn't you use validates_format_of instead? — 200_success
– 200_success, Commented Jan 26, 2016 at 1:06

Mihai-Andrei Dinculescu · Accepted Answer · 2016-01-25 23:26:42Z

5

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

edited Jan 25, 2016 at 23:26

answered Jan 25, 2016 at 23:19

Mihai-Andrei Dinculescu

1511 silver badge8 bronze badges

1

\$\begingroup\$ Welcome to Code Review! Good job on your first answer \$\endgroup\$

SirPython
– SirPython

2016-01-25 23:35:08 +00:00
Commented Jan 25, 2016 at 23:35
\$\begingroup\$ The other reason to keep valid? public is that you can unit test it. \$\endgroup\$

Thomas Andrews
– Thomas Andrews

2016-01-28 05:04:25 +00:00
Commented Jan 28, 2016 at 5:04

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