ActiveModel::Validations::HelperMethods

@fowlduck You can get a link to a method, but requires opening the frame in a new window. Example:

Encapsulates the pattern of wanting to validate a password or email address field with a confirmation. For example: Model: class Person < ActiveRecord::Base validates_confirmation_of :user_name, :password validates_confirmation_of :email_address, :message => "should match confirmation" end View: <%= password_field "person", "password" %> <%= password_field "person", "password_confirmation" %> The added password_confirmation attribute is virtual; it exists only as an in-memory attribute for validating the password. To achieve this, the validation adds accessors to the model for the confirmation attribute. NOTE: This check is performed only if password_confirmation is not nil , and by default only on save. To require confirmation, make sure to add a presence check for the confirmation attribute: validates_presence_of :password_confirmation , :if => :password_changed? Configu...

Full article: http://api.rubyonrails.org/classes/ActiveModel/Validation...