When you create a Web site or Web application with Ruby on Rails, you need to make sure that you input data in a form that Rails recognizes and can use. The following table contains Rails validation helpers:

validates_acceptance_of validates_inclusion_of
validates_associated validates_length_of
validates_confirmation_of validates_numericality_of
validates_each validates_presence_of
validates_exclusion_of validates_size_of
validates_format_of validates_uniqueness_of