Ruby on Rails Validation Helpers

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

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Source:http://www.dummies.com/how-to/content/ruby-on-rails-validation-helpers.navId-323192.html