| Module | ActiveRecord::Validations::ClassMethods |
| In: |
vendor/rails/activerecord/lib/active_record/validations.rb
|
Active Record classes can implement validations in several ways. The highest level, easiest to read, and recommended approach is to use the declarative validates_..._of class methods (and validates_associated) documented below. These are sufficient for most model validations.
Slightly lower level is validates_each. It provides some of the same options as the purely declarative validation methods, but like all the lower-level approaches it requires manually adding to the errors collection when the record is invalid.
At a yet lower level, a model can use the class methods validate, validate_on_create and validate_on_update to add validation methods or blocks. These are ActiveSupport::Callbacks and follow the same rules of inheritance and chaining.
The lowest level style is to define the instance methods validate, validate_on_create and validate_on_update as documented in ActiveRecord::Validations.
Calls to these methods add a validation method or block to the class. Again, this approach is recommended only when the higher-level methods documented below (validates_..._of and validates_associated) are insufficient to handle the required validation.
This can be done with a symbol pointing to a method:
class Comment < ActiveRecord::Base
validate :must_be_friends
def must_be_friends
errors.add_to_base("Must be friends to leave a comment") unless commenter.friend_of?(commentee)
end
end
Or with a block which is passed the current record to be validated:
class Comment < ActiveRecord::Base
validate do |comment|
comment.must_be_friends
end
def must_be_friends
errors.add_to_base("Must be friends to leave a comment") unless commenter.friend_of?(commentee)
end
end
This usage applies to validate_on_create and validate_on_update as well.
| DEFAULT_VALIDATION_OPTIONS | = | { :on => :save, :allow_nil => false, :allow_blank => false, :message => nil |
| ALL_RANGE_OPTIONS | = | [ :is, :within, :in, :minimum, :maximum ].freeze |
| ALL_NUMERICALITY_CHECKS | = | { :greater_than => '>', :greater_than_or_equal_to => '>=', :equal_to => '==', :less_than => '<', :less_than_or_equal_to => '<=', :odd => 'odd?', :even => 'even?' }.freeze |
Creates an object just like Base.create but calls save! instead of save so an exception is raised if the record is invalid.
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 1053
1053: def create!(attributes = nil, &block)
1054: if attributes.is_a?(Array)
1055: attributes.collect { |attr| create!(attr, &block) }
1056: else
1057: object = new(attributes)
1058: yield(object) if block_given?
1059: object.save!
1060: object
1061: end
1062: end
Encapsulates the pattern of wanting to validate the acceptance of a terms of service check box (or similar agreement). Example:
class Person < ActiveRecord::Base
validates_acceptance_of :terms_of_service
validates_acceptance_of :eula, :message => "must be abided"
end
If the database column does not exist, the terms_of_service attribute is entirely virtual. This check is performed only if terms_of_service is not nil and by default on save.
Configuration options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 537
537: def validates_acceptance_of(*attr_names)
538: configuration = { :on => :save, :allow_nil => true, :accept => "1" }
539: configuration.update(attr_names.extract_options!)
540:
541: db_cols = begin
542: column_names
543: rescue Exception # To ignore both statement and connection errors
544: []
545: end
546: names = attr_names.reject { |name| db_cols.include?(name.to_s) }
547: attr_accessor(*names)
548:
549: validates_each(attr_names,configuration) do |record, attr_name, value|
550: unless value == configuration[:accept]
551: record.errors.add(attr_name, :accepted, :default => configuration[:message])
552: end
553: end
554: end
Validates whether the associated object or objects are all valid themselves. Works with any kind of association.
class Book < ActiveRecord::Base
has_many :pages
belongs_to :library
validates_associated :pages, :library
end
Warning: If, after the above definition, you then wrote:
class Page < ActiveRecord::Base
belongs_to :book
validates_associated :book
end
this would specify a circular dependency and cause infinite recursion.
NOTE: This validation will not fail if the association hasn‘t been assigned. If you want to ensure that the association is both present and guaranteed to be valid, you also need to use validates_presence_of.
Configuration options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 970
970: def validates_associated(*attr_names)
971: configuration = { :on => :save }
972: configuration.update(attr_names.extract_options!)
973:
974: validates_each(attr_names, configuration) do |record, attr_name, value|
975: unless (value.is_a?(Array) ? value : [value]).collect { |r| r.nil? || r.valid? }.all?
976: record.errors.add(attr_name, :invalid, :default => configuration[:message], :value => value)
977: end
978: end
979: end
Encapsulates the pattern of wanting to validate a password or email address field with a confirmation. 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?
Configuration options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 501
501: def validates_confirmation_of(*attr_names)
502: configuration = { :on => :save }
503: configuration.update(attr_names.extract_options!)
504:
505: attr_accessor(*(attr_names.map { |n| "#{n}_confirmation" }))
506:
507: validates_each(attr_names, configuration) do |record, attr_name, value|
508: unless record.send("#{attr_name}_confirmation").nil? or value == record.send("#{attr_name}_confirmation")
509: record.errors.add(attr_name, :confirmation, :default => configuration[:message])
510: end
511: end
512: end
Validates each attribute against a block.
class Person < ActiveRecord::Base
validates_each :first_name, :last_name do |record, attr, value|
record.errors.add attr, 'starts with z.' if value[0] == ?z
end
end
Options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 459
459: def validates_each(*attrs)
460: options = attrs.extract_options!.symbolize_keys
461: attrs = attrs.flatten
462:
463: # Declare the validation.
464: send(validation_method(options[:on] || :save), options) do |record|
465: attrs.each do |attr|
466: value = record.send(attr)
467: next if (value.nil? && options[:allow_nil]) || (value.blank? && options[:allow_blank])
468: yield record, attr, value
469: end
470: end
471: end
Validates that the value of the specified attribute is not in a particular enumerable object.
class Person < ActiveRecord::Base
validates_exclusion_of :username, :in => %w( admin superuser ), :message => "You don't belong here"
validates_exclusion_of :age, :in => 30..60, :message => "This site is only for under 30 and over 60"
validates_exclusion_of :format, :in => %w( mov avi ), :message => "extension {{value}} is not allowed"
end
Configuration options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 924
924: def validates_exclusion_of(*attr_names)
925: configuration = { :on => :save }
926: configuration.update(attr_names.extract_options!)
927:
928: enum = configuration[:in] || configuration[:within]
929:
930: raise(ArgumentError, "An object with the method include? is required must be supplied as the :in option of the configuration hash") unless enum.respond_to?(:include?)
931:
932: validates_each(attr_names, configuration) do |record, attr_name, value|
933: if enum.include?(value)
934: record.errors.add(attr_name, :exclusion, :default => configuration[:message], :value => value)
935: end
936: end
937: end
Validates whether the value of the specified attribute is of the correct form by matching it against the regular expression provided.
class Person < ActiveRecord::Base
validates_format_of :email, :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i, :on => :create
end
Note: use \A and \Z to match the start and end of the string, ^ and $ match the start/end of a line.
A regular expression must be provided or else an exception will be raised.
Configuration options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 858
858: def validates_format_of(*attr_names)
859: configuration = { :on => :save, :with => nil }
860: configuration.update(attr_names.extract_options!)
861:
862: raise(ArgumentError, "A regular expression must be supplied as the :with option of the configuration hash") unless configuration[:with].is_a?(Regexp)
863:
864: validates_each(attr_names, configuration) do |record, attr_name, value|
865: unless value.to_s =~ configuration[:with]
866: record.errors.add(attr_name, :invalid, :default => configuration[:message], :value => value)
867: end
868: end
869: end
Validates whether the value of the specified attribute is available in a particular enumerable object.
class Person < ActiveRecord::Base
validates_inclusion_of :gender, :in => %w( m f )
validates_inclusion_of :age, :in => 0..99
validates_inclusion_of :format, :in => %w( jpg gif png ), :message => "extension {{value}} is not included in the list"
end
Configuration options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 890
890: def validates_inclusion_of(*attr_names)
891: configuration = { :on => :save }
892: configuration.update(attr_names.extract_options!)
893:
894: enum = configuration[:in] || configuration[:within]
895:
896: raise(ArgumentError, "An object with the method include? is required must be supplied as the :in option of the configuration hash") unless enum.respond_to?(:include?)
897:
898: validates_each(attr_names, configuration) do |record, attr_name, value|
899: unless enum.include?(value)
900: record.errors.add(attr_name, :inclusion, :default => configuration[:message], :value => value)
901: end
902: end
903: end
Validates that the specified attribute matches the length restrictions supplied. Only one option can be used at a time:
class Person < ActiveRecord::Base
validates_length_of :first_name, :maximum=>30
validates_length_of :last_name, :maximum=>30, :message=>"less than {{count}} if you don't mind"
validates_length_of :fax, :in => 7..32, :allow_nil => true
validates_length_of :phone, :in => 7..32, :allow_blank => true
validates_length_of :user_name, :within => 6..20, :too_long => "pick a shorter name", :too_short => "pick a longer name"
validates_length_of :fav_bra_size, :minimum => 1, :too_short => "please enter at least {{count}} character"
validates_length_of :smurf_leader, :is => 4, :message => "papa is spelled with {{count}} characters... don't play me."
validates_length_of :essay, :minimum => 100, :too_short => "Your essay must be at least {{count}} words."), :tokenizer => lambda {|str| str.scan(/\w+/) }
end
Configuration options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 626
626: def validates_length_of(*attrs)
627: # Merge given options with defaults.
628: options = {
629: :tokenizer => lambda {|value| value.split(//)}
630: }.merge(DEFAULT_VALIDATION_OPTIONS)
631: options.update(attrs.extract_options!.symbolize_keys)
632:
633: # Ensure that one and only one range option is specified.
634: range_options = ALL_RANGE_OPTIONS & options.keys
635: case range_options.size
636: when 0
637: raise ArgumentError, 'Range unspecified. Specify the :within, :maximum, :minimum, or :is option.'
638: when 1
639: # Valid number of options; do nothing.
640: else
641: raise ArgumentError, 'Too many range options specified. Choose only one.'
642: end
643:
644: # Get range option and value.
645: option = range_options.first
646: option_value = options[range_options.first]
647: key = {:is => :wrong_length, :minimum => :too_short, :maximum => :too_long}[option]
648: custom_message = options[:message] || options[key]
649:
650: case option
651: when :within, :in
652: raise ArgumentError, ":#{option} must be a Range" unless option_value.is_a?(Range)
653:
654: validates_each(attrs, options) do |record, attr, value|
655: value = options[:tokenizer].call(value) if value.kind_of?(String)
656: if value.nil? or value.size < option_value.begin
657: record.errors.add(attr, :too_short, :default => custom_message || options[:too_short], :count => option_value.begin)
658: elsif value.size > option_value.end
659: record.errors.add(attr, :too_long, :default => custom_message || options[:too_long], :count => option_value.end)
660: end
661: end
662: when :is, :minimum, :maximum
663: raise ArgumentError, ":#{option} must be a nonnegative Integer" unless option_value.is_a?(Integer) and option_value >= 0
664:
665: # Declare different validations per option.
666: validity_checks = { :is => "==", :minimum => ">=", :maximum => "<=" }
667:
668: validates_each(attrs, options) do |record, attr, value|
669: value = options[:tokenizer].call(value) if value.kind_of?(String)
670: unless !value.nil? and value.size.method(validity_checks[option])[option_value]
671: record.errors.add(attr, key, :default => custom_message, :count => option_value)
672: end
673: end
674: end
675: end
Validates whether the value of the specified attribute is numeric by trying to convert it to a float with Kernel.Float (if only_integer is false) or applying it to the regular expression /\A[+\-]?\d+\Z/ (if only_integer is set to true).
class Person < ActiveRecord::Base
validates_numericality_of :value, :on => :create
end
Configuration options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 1007
1007: def validates_numericality_of(*attr_names)
1008: configuration = { :on => :save, :only_integer => false, :allow_nil => false }
1009: configuration.update(attr_names.extract_options!)
1010:
1011:
1012: numericality_options = ALL_NUMERICALITY_CHECKS.keys & configuration.keys
1013:
1014: (numericality_options - [ :odd, :even ]).each do |option|
1015: raise ArgumentError, ":#{option} must be a number" unless configuration[option].is_a?(Numeric)
1016: end
1017:
1018: validates_each(attr_names,configuration) do |record, attr_name, value|
1019: raw_value = record.send("#{attr_name}_before_type_cast") || value
1020:
1021: next if configuration[:allow_nil] and raw_value.nil?
1022:
1023: if configuration[:only_integer]
1024: unless raw_value.to_s =~ /\A[+-]?\d+\Z/
1025: record.errors.add(attr_name, :not_a_number, :value => raw_value, :default => configuration[:message])
1026: next
1027: end
1028: raw_value = raw_value.to_i
1029: else
1030: begin
1031: raw_value = Kernel.Float(raw_value)
1032: rescue ArgumentError, TypeError
1033: record.errors.add(attr_name, :not_a_number, :value => raw_value, :default => configuration[:message])
1034: next
1035: end
1036: end
1037:
1038: numericality_options.each do |option|
1039: case option
1040: when :odd, :even
1041: unless raw_value.to_i.method(ALL_NUMERICALITY_CHECKS[option])[]
1042: record.errors.add(attr_name, option, :value => raw_value, :default => configuration[:message])
1043: end
1044: else
1045: record.errors.add(attr_name, option, :default => configuration[:message], :value => raw_value, :count => configuration[option]) unless raw_value.method(ALL_NUMERICALITY_CHECKS[option])[configuration[option]]
1046: end
1047: end
1048: end
1049: end
Validates that the specified attributes are not blank (as defined by Object#blank?). Happens by default on save. Example:
class Person < ActiveRecord::Base
validates_presence_of :first_name
end
The first_name attribute must be in the object and it cannot be blank.
If you want to validate the presence of a boolean field (where the real values are true and false), you will want to use validates_inclusion_of :field_name, :in => [true, false].
This is due to the way Object#blank? handles boolean values: false.blank? # => true.
Configuration options:
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 580
580: def validates_presence_of(*attr_names)
581: configuration = { :on => :save }
582: configuration.update(attr_names.extract_options!)
583:
584: # can't use validates_each here, because it cannot cope with nonexistent attributes,
585: # while errors.add_on_empty can
586: send(validation_method(configuration[:on]), configuration) do |record|
587: record.errors.add_on_blank(attr_names, configuration[:message])
588: end
589: end
Validates whether the value of the specified attributes are unique across the system. Useful for making sure that only one user can be named "davidhh".
class Person < ActiveRecord::Base
validates_uniqueness_of :user_name, :scope => :account_id
end
It can also validate whether the value of the specified attributes are unique based on multiple scope parameters. For example, making sure that a teacher can only be on the schedule once per semester for a particular class.
class TeacherSchedule < ActiveRecord::Base
validates_uniqueness_of :teacher_id, :scope => [:semester_id, :class_id]
end
When the record is created, a check is performed to make sure that no record exists in the database with the given value for the specified attribute (that maps to a column). When the record is updated, the same check is made but disregarding the record itself.
Configuration options:
Using this validation method in conjunction with ActiveRecord::Base#save does not guarantee the absence of duplicate record insertions, because uniqueness checks on the application level are inherently prone to race conditions. For example, suppose that two users try to post a Comment at the same time, and a Comment‘s title must be unique. At the database-level, the actions performed by these users could be interleaved in the following manner:
User 1 | User 2
------------------------------------+--------------------------------------
# User 1 checks whether there's |
# already a comment with the title |
# 'My Post'. This is not the case. |
SELECT * FROM comments |
WHERE title = 'My Post' |
|
| # User 2 does the same thing and also
| # infers that his title is unique.
| SELECT * FROM comments
| WHERE title = 'My Post'
|
# User 1 inserts his comment. |
INSERT INTO comments |
(title, content) VALUES |
('My Post', 'hi!') |
|
| # User 2 does the same thing.
| INSERT INTO comments
| (title, content) VALUES
| ('My Post', 'hello!')
|
| # ^^^^^^
| # Boom! We now have a duplicate
| # title!
This could even happen if you use transactions with the ‘serializable’ isolation level. There are several ways to get around this problem:
When the database catches such a duplicate insertion, ActiveRecord::Base#save will raise an ActiveRecord::StatementInvalid exception. You can either choose to let this error propagate (which will result in the default Rails exception page being shown), or you can catch it and restart the transaction (e.g. by telling the user that the title already exists, and asking him to re-enter the title). This technique is also known as optimistic concurrency control: en.wikipedia.org/wiki/Optimistic_concurrency_control
Active Record currently provides no way to distinguish unique index constraint errors from other types of database errors, so you will have to parse the (database-specific) exception message to detect such a case.
# File vendor/rails/activerecord/lib/active_record/validations.rb, line 773
773: def validates_uniqueness_of(*attr_names)
774: configuration = { :case_sensitive => true }
775: configuration.update(attr_names.extract_options!)
776:
777: validates_each(attr_names,configuration) do |record, attr_name, value|
778: # The check for an existing value should be run from a class that
779: # isn't abstract. This means working down from the current class
780: # (self), to the first non-abstract class. Since classes don't know
781: # their subclasses, we have to build the hierarchy between self and
782: # the record's class.
783: class_hierarchy = [record.class]
784: while class_hierarchy.first != self
785: class_hierarchy.insert(0, class_hierarchy.first.superclass)
786: end
787:
788: # Now we can work our way down the tree to the first non-abstract
789: # class (which has a database table to query from).
790: finder_class = class_hierarchy.detect { |klass| !klass.abstract_class? }
791:
792: column = finder_class.columns_hash[attr_name.to_s]
793:
794: if value.nil?
795: comparison_operator = "IS ?"
796: elsif column.text?
797: comparison_operator = "#{connection.case_sensitive_equality_operator} ?"
798: value = column.limit ? value.to_s.mb_chars[0, column.limit] : value.to_s
799: else
800: comparison_operator = "= ?"
801: end
802:
803: sql_attribute = "#{record.class.quoted_table_name}.#{connection.quote_column_name(attr_name)}"
804:
805: if value.nil? || (configuration[:case_sensitive] || !column.text?)
806: condition_sql = "#{sql_attribute} #{comparison_operator}"
807: condition_params = [value]
808: else
809: condition_sql = "LOWER(#{sql_attribute}) #{comparison_operator}"
810: condition_params = [value.mb_chars.downcase]
811: end
812:
813: if scope = configuration[:scope]
814: Array(scope).map do |scope_item|
815: scope_value = record.send(scope_item)
816: condition_sql << " AND " << attribute_condition("#{record.class.quoted_table_name}.#{scope_item}", scope_value)
817: condition_params << scope_value
818: end
819: end
820:
821: unless record.new_record?
822: condition_sql << " AND #{record.class.quoted_table_name}.#{record.class.primary_key} <> ?"
823: condition_params << record.send(:id)
824: end
825:
826: finder_class.with_exclusive_scope do
827: if finder_class.exists?([condition_sql, *condition_params])
828: record.errors.add(attr_name, :taken, :default => configuration[:message], :value => value)
829: end
830: end
831: end
832: end