= SixArm.com » Ruby » Email address validation using RFC 822 pattern matching

Author:: Joel Parker Henderson, joel@joelparkerhenderson.com
Copyright:: Copyright (c) 2006-2011 Joel Parker Henderson
License:: See LICENSE.txt file

Email address regular expression to validate an email address using RFC 822.

This is a gem wrapper around http://tfletcher.com/lib/rfc822.rb

Example:
  if EMAIL_ADDRESS_INNER_PATTERN=~'foo@bar.com'
    puts "found" 
  else
    puts "not found"
  end
  => found


== Pattern Match

To find an email address in a string, do the pattern match
then use the result, which is the match's string position:

Example of match position:
  match_position = EMAIL_ADDRESS_INNER_PATTERN=~'foo@bar.com'
  => 0

  match_position = EMAIL_ADDRESS_INNER_PATTERN=~'... foo@bar.com ...'
  => 4

  match_position = EMAIL_ADDRESS_INNER_PATTERN=~'... hello world ...'
  => nil


== Exact Pattern Match

To do an exact pattern match, use the EMAIL_ADDRESS_EXACT_PATTERN.
This matches the entire string from start to end; in other words,
the entire string must be one email address.

Example of exact pattern match:
  if EMAIL_ADDRESS_EXACT_PATTERN=~'foo@bar.com' 
    puts "found" 
  else
    puts "not found"
  end
  => found

  if EMAIL_ADDRESS_EXACT_PATTERN=~'... foo@bar.com ...' 
    puts "found" 
  else
    puts "not found"
  end
  => not found

The exact pattern is especialy useful to validate an email address.

Example to validate an email address:
  def valid?(email_address)
    EMAIL_ADDRESS_EXACT_PATTERN=~email_address ? true : false
  end


== Rails Validation

To add email address validation to a typical Ruby On Rails model:

  class User
    include EmailAddressValidation
    validates :email_address, :format => { :with => EMAIL_ADDRESS_EXACT_PATTERN },
  end