validates_as_hostname_label

Checks for valid hostname labels by looking for:

• Length between 1 and 63 characters long
• Letters 'a' through 'z' (case-insensitive), the digits '0' through '9', and the hyphen (and optionally the underscore)
• Labels that don't begin or end with a hyphen or underscore
• Reserved labels

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

Installation

gem install shuber-validates_as_hostname_label --source http://gems.github.com
OR
script/plugin install git://github.com/shuber/validates_as_hostname_label.git

Usage

class Account < ActiveRecord::Base
  validates_as_hostname_label :subdomain
end

You may optionally pass a :reserved option which should be an array of hostname labels to exclude, otherwise Huberry::ValidatesAsHostnameLabel::RESERVED_HOSTNAMES 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 usual validation options (like :if, :unless, :allow_nil, etc) work as well

Contact

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