Rails Validation

RailsValidation.rb

validates_presence_of
# Attribute must not be blank (nil, false, "", " ",[] ,{})
# :message => "can't be blank"

validates_length_of
# Attribute must meet the length requirements of the options
# :is, :minimum(integer)
# :within, :in(range)
# :wrong_length => "is the wrong length (should be {{count}} characters)"
# :too_short => "is too short (minimum is {{count}} characters)"
# :too_long => "is too long (maximum is {{count}} characters)"

validates_numericality_of
# Attribute must be an integer or a floating point number
# :equal_to, :greater_than, :less_than, :greater_than_or_equal_to, :less_than_or_equal_to(numeric)
# :odd, :even, :only_integer(boolean)
# :message => "is not a number"

validates_inclusion_of
# Attribute must be in a list of choices (an array or range)
# :in(enumerable)
# :message => "is not included in the list"

validates_exclusion_of
# Attribute must not be in the list of choices (an array or range)
# :in(enumerable)
# :message => "is reserved"

validates_format_of
# Attribute must match a regular expression
# :with(regular expression)
# :message => "is invalid"

validates_uniqueness_of
# Attribute must not already exist in the database(for the given scope)
# :case_sensitive(boolean)
# :scope(column symbols for limiting scope)
# :message => "has already been taken"

validates_acceptance_of
# Attribute must be "accepted"
# Creates a virtual attribute if there is no table column for the attribute
# :accept(expected value, "1")
# :message => "must be accepted"

validates_confirmation_of
# Attribute must be confirmed by entering it twice
# Creates a virtual attribute for the confirmation (:email gets :email_confirmation)
# Only validates when confirmation attribute is not nil (no confirm form field submitted = no validation)
# :message => "doesn't match confirmation"

#Options
 :allow_nil => true
# Skips validation if the attribute is nil (no value set)
 :allow_blank => true
# Skips validation if attribute is blank (nil, false, "", " ", [], {})
 :on => :save / :create / :update
# Only validates if this is a new record(:create) or an existing record (:update)
# :save validates in both cases and is the default
 :if => :method / :unless => :method
# :method is a method defined in the model that should return true or false

#Rails 3 Method for combining validations
validates :email, :presence => true,
                  :length => { :maximum => 50 },
                  :uniqueness => true,
                  :format => { :with => EMAIL_REGEX },
                  :confirmation => true

validates_associated(association, options)
# Associated object or objects must all be valid
# :message => "is invalid"
# :on => save / :create / :update, :if => method, :unless => method
                  
#cannot be used with Rails 3 combined validations