validates_as_hostname_label¶ ↑

Checks for valid hostname labels by looking for:

• Length between 1 and 63 characters long

• Alphanumeric, hyphen, and (optionally) underscore characters

• Labels that don’t begin or end with a hyphen or underscore

• Reserved labels

See en.wikipedia.org/wiki/Hostname#Restrictions_on_valid_host_names

gem install validates_as_hostname_label
OR
script/plugin install git://github.com/shuber/validates_as_hostname_label.git

class Account < ActiveRecord::Base
  validates_as_hostname_label :subdomain
end

@account = Account.new
@account.save # false
@account.errors # { :subdomain => 'is required' }

You may optionally pass a :reserved option which should be an array of hostname labels to exclude, otherwise ValidatesAsHostnameLabel.default_options[:reserved] will be used.

class Account < ActiveRecord::Base
  validates_as_hostname_label :subdomain, :reserved => ['www', 'ftp', 'mail', 'pop']
end

@account = Account.new :subdomain => 'www'
@account.save # false
@account.errors # { :subdomain => 'is reserved' }

Also accepts an :allow_underscores option which defaults to false.

class Account < ActiveRecord::Base
  validates_as_hostname_label :subdomain, :allow_underscores => true
end

@account = Account.new :subdomain => 'test_ing'
@account.save # true

The standard validation options :if, :unless, and :allow_blank work as well.

Uses the following I18n keys:

• validates_as_hostname_label.invalid_format

• validates_as_hostname_label.invalid_length

• validates_as_hostname_label.invalid_prefix_or_suffix

• validates_as_hostname_label.reserved

• Fork the project.

• Make your feature addition or bug fix.

• Add tests for it. This is important so I don’t break it in a future version unintentionally.

• Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but

  bump version in a commit by itself I can ignore when I pull)

• Send me a pull request. Bonus points for topic branches.

Problems, comments, and suggestions all welcome: shuber@huberry.com