Module: ActiveRecord::Validations::ClassMethods
- Defined in:
- lib/active_record/validations.rb
Overview
All of the following validations are defined in the class scope of the model that you’re interested in validating. They offer a more declarative way of specifying when the model is valid and when it is not. It is recommended to use these over the low-level calls to validate and validate_on_create when possible.
Constant Summary collapse
- DEFAULT_VALIDATION_OPTIONS =
{ :on => :save, :allow_nil => false, :allow_blank => false, :message => nil }.freeze
- 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
Instance Method Summary collapse
- #condition_block?(condition) ⇒ Boolean
-
#create!(attributes = nil) ⇒ Object
Creates an object just like Base.create but calls save! instead of save so an exception is raised if the record is invalid.
-
#evaluate_condition(condition, record) ⇒ Object
Determine from the given condition (whether a block, procedure, method or string) whether or not to validate the record.
- #validate(*methods, &block) ⇒ Object
- #validate_on_create(*methods, &block) ⇒ Object
- #validate_on_update(*methods, &block) ⇒ Object
-
#validates_acceptance_of(*attr_names) ⇒ Object
Encapsulates the pattern of wanting to validate the acceptance of a terms of service check box (or similar agreement).
-
#validates_associated(*attr_names) ⇒ Object
Validates whether the associated object or objects are all valid themselves.
-
#validates_confirmation_of(*attr_names) ⇒ Object
Encapsulates the pattern of wanting to validate a password or email address field with a confirmation.
-
#validates_each(*attrs) ⇒ Object
Validates each attribute against a block.
-
#validates_exclusion_of(*attr_names) ⇒ Object
Validates that the value of the specified attribute is not in a particular enumerable object.
-
#validates_format_of(*attr_names) ⇒ Object
Validates whether the value of the specified attribute is of the correct form by matching it against the regular expression provided.
-
#validates_inclusion_of(*attr_names) ⇒ Object
Validates whether the value of the specified attribute is available in a particular enumerable object.
-
#validates_length_of(*attrs) ⇒ Object
(also: #validates_size_of)
Validates that the specified attribute matches the length restrictions supplied.
-
#validates_numericality_of(*attr_names) ⇒ Object
Validates whether the value of the specified attribute is numeric by trying to convert it to a float with Kernel.Float (if
integer
is false) or applying it to the regular expression/\A[+\-]?\d+\Z/
(ifinteger
is set to true). -
#validates_presence_of(*attr_names) ⇒ Object
Validates that the specified attributes are not blank (as defined by Object#blank?).
-
#validates_uniqueness_of(*attr_names) ⇒ Object
Validates whether the value of the specified attributes are unique across the system.
Instance Method Details
#condition_block?(condition) ⇒ Boolean
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# File 'lib/active_record/validations.rb', line 316 def condition_block?(condition) condition.respond_to?("call") && (condition.arity == 1 || condition.arity == -1) end |
#create!(attributes = nil) ⇒ Object
Creates an object just like Base.create but calls save! instead of save so an exception is raised if the record is invalid.
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# File 'lib/active_record/validations.rb', line 871 def create!(attributes = nil) if attributes.is_a?(Array) attributes.collect { |attr| create!(attr) } else object = new(attributes) object.save! object end end |
#evaluate_condition(condition, record) ⇒ Object
Determine from the given condition (whether a block, procedure, method or string) whether or not to validate the record. See #validates_each.
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# File 'lib/active_record/validations.rb', line 322 def evaluate_condition(condition, record) case condition when Symbol; record.send(condition) when String; eval(condition, record.send(:binding)) else if condition_block?(condition) condition.call(record) else raise( ActiveRecordError, "Validations need to be either a symbol, string (to be eval'ed), proc/method, or " + "class implementing a static validation method" ) end end end |
#validate(*methods, &block) ⇒ Object
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# File 'lib/active_record/validations.rb', line 301 def validate(*methods, &block) methods << block if block_given? write_inheritable_set(:validate, methods) end |
#validate_on_create(*methods, &block) ⇒ Object
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# File 'lib/active_record/validations.rb', line 306 def validate_on_create(*methods, &block) methods << block if block_given? write_inheritable_set(:validate_on_create, methods) end |
#validate_on_update(*methods, &block) ⇒ Object
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# File 'lib/active_record/validations.rb', line 311 def validate_on_update(*methods, &block) methods << block if block_given? write_inheritable_set(:validate_on_update, methods) end |
#validates_acceptance_of(*attr_names) ⇒ Object
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:
-
message
- A custom error message (default is: “must be accepted”) -
on
- Specifies when this validation is active (default is :save, other options :create, :update) -
allow_nil
- Skip validation if attribute is nil. (default is true) -
accept
- Specifies value that is considered accepted. The default value is a string “1”, which makes it easy to relate to an HTML checkbox. -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 435 def validates_acceptance_of(*attr_names) configuration = { :message => ActiveRecord::Errors.[:accepted], :on => :save, :allow_nil => true, :accept => "1" } configuration.update(attr_names.) attr_accessor *attr_names.reject { |name| column_names.include? name.to_s } validates_each(attr_names,configuration) do |record, attr_name, value| record.errors.add(attr_name, configuration[:message]) unless value == configuration[:accept] end end |
#validates_associated(*attr_names) ⇒ Object
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:
-
message
- A custom error message (default is: “is invalid”) -
on
Specifies when this validation is active (default is :save, other options :create, :update) -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 791 def validates_associated(*attr_names) configuration = { :message => ActiveRecord::Errors.[:invalid], :on => :save } configuration.update(attr_names.) validates_each(attr_names, configuration) do |record, attr_name, value| record.errors.add(attr_name, configuration[:message]) unless (value.is_a?(Array) ? value : [value]).inject(true) { |v, r| (r.nil? || r.valid?) && v } end end |
#validates_confirmation_of(*attr_names) ⇒ Object
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 acccessors 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:
-
message
- A custom error message (default is: “doesn’t match confirmation”) -
on
- Specifies when this validation is active (default is :save, other options :create, :update) -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 402 def validates_confirmation_of(*attr_names) configuration = { :message => ActiveRecord::Errors.[:confirmation], :on => :save } configuration.update(attr_names.) attr_accessor *(attr_names.map { |n| "#{n}_confirmation" }) validates_each(attr_names, configuration) do |record, attr_name, value| record.errors.add(attr_name, configuration[:message]) unless record.send("#{attr_name}_confirmation").nil? or value == record.send("#{attr_name}_confirmation") end end |
#validates_each(*attrs) ⇒ Object
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:
-
on
- Specifies when this validation is active (default is :save, other options :create, :update) -
allow_nil
- Skip validation if attribute is nil. -
allow_blank
- Skip validation if attribute is blank. -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 357 def validates_each(*attrs) = attrs..symbolize_keys attrs = attrs.flatten # Declare the validation. send(validation_method([:on] || :save)) do |record| # Don't validate when there is an :if condition and that condition is false or there is an :unless condition and that condition is true unless ([:if] && !evaluate_condition([:if], record)) || ([:unless] && evaluate_condition([:unless], record)) attrs.each do |attr| value = record.send(attr) next if (value.nil? && [:allow_nil]) || (value.blank? && [:allow_blank]) yield record, attr, value end end end end |
#validates_exclusion_of(*attr_names) ⇒ Object
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 %s is not allowed"
end
Configuration options:
-
in
- An enumerable object of items that the value shouldn’t be part of -
message
- Specifies a customer error message (default is: “is reserved”) -
allow_nil
- If set to true, skips this validation if the attribute is null (default is: false) -
allow_blank
- If set to true, skips this validation if the attribute is blank (default is: false) -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 747 def validates_exclusion_of(*attr_names) configuration = { :message => ActiveRecord::Errors.[:exclusion], :on => :save } configuration.update(attr_names.) enum = configuration[:in] || configuration[:within] 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?") validates_each(attr_names, configuration) do |record, attr_name, value| record.errors.add(attr_name, configuration[:message] % value) if enum.include?(value) end end |
#validates_format_of(*attr_names) ⇒ Object
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:
-
message
- A custom error message (default is: “is invalid”) -
with
- The regular expression used to validate the format with (note: must be supplied!) -
on
Specifies when this validation is active (default is :save, other options :create, :update) -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 685 def validates_format_of(*attr_names) configuration = { :message => ActiveRecord::Errors.[:invalid], :on => :save, :with => nil } configuration.update(attr_names.) raise(ArgumentError, "A regular expression must be supplied as the :with option of the configuration hash") unless configuration[:with].is_a?(Regexp) validates_each(attr_names, configuration) do |record, attr_name, value| record.errors.add(attr_name, configuration[:message]) unless value.to_s =~ configuration[:with] end end |
#validates_inclusion_of(*attr_names) ⇒ Object
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 ), :message => "woah! what are you then!??!!"
validates_inclusion_of :age, :in => 0..99
validates_inclusion_of :format, :in => %w( jpg gif png ), :message => "extension %s is not included in the list"
end
Configuration options:
-
in
- An enumerable object of available items -
message
- Specifies a customer error message (default is: “is not included in the list”) -
allow_nil
- If set to true, skips this validation if the attribute is null (default is: false) -
allow_blank
- If set to true, skips this validation if the attribute is blank (default is: false) -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 715 def validates_inclusion_of(*attr_names) configuration = { :message => ActiveRecord::Errors.[:inclusion], :on => :save } configuration.update(attr_names.) enum = configuration[:in] || configuration[:within] 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?") validates_each(attr_names, configuration) do |record, attr_name, value| record.errors.add(attr_name, configuration[:message] % value) unless enum.include?(value) end end |
#validates_length_of(*attrs) ⇒ Object Also known as: validates_size_of
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 %d 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 %d character"
validates_length_of :smurf_leader, :is=>4, :message=>"papa is spelled with %d characters... don't play me."
end
Configuration options:
-
minimum
- The minimum size of the attribute -
maximum
- The maximum size of the attribute -
is
- The exact size of the attribute -
within
- A range specifying the minimum and maximum size of the attribute -
in
- A synonym(or alias) for :within -
allow_nil
- Attribute may be nil; skip validation. -
allow_blank
- Attribute may be blank; skip validation. -
too_long
- The error message if the attribute goes over the maximum (default is: “is too long (maximum is %d characters)”) -
too_short
- The error message if the attribute goes under the minimum (default is: “is too short (min is %d characters)”) -
wrong_length
- The error message if using the :is method and the attribute is the wrong size (default is: “is the wrong length (should be %d characters)”) -
message
- The error message to use for a :minimum, :maximum, or :is violation. An alias of the appropriate too_long/too_short/wrong_length message -
on
- Specifies when this validation is active (default is :save, other options :create, :update) -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 524 def validates_length_of(*attrs) # Merge given options with defaults. = { :too_long => ActiveRecord::Errors.[:too_long], :too_short => ActiveRecord::Errors.[:too_short], :wrong_length => ActiveRecord::Errors.[:wrong_length] }.merge(DEFAULT_VALIDATION_OPTIONS) .update(attrs..symbolize_keys) # Ensure that one and only one range option is specified. = ALL_RANGE_OPTIONS & .keys case .size when 0 raise ArgumentError, 'Range unspecified. Specify the :within, :maximum, :minimum, or :is option.' when 1 # Valid number of options; do nothing. else raise ArgumentError, 'Too many range options specified. Choose only one.' end # Get range option and value. option = .first option_value = [.first] case option when :within, :in raise ArgumentError, ":#{option} must be a Range" unless option_value.is_a?(Range) too_short = [:too_short] % option_value.begin too_long = [:too_long] % option_value.end validates_each(attrs, ) do |record, attr, value| if value.nil? or value.split(//).size < option_value.begin record.errors.add(attr, too_short) elsif value.split(//).size > option_value.end record.errors.add(attr, too_long) end end when :is, :minimum, :maximum raise ArgumentError, ":#{option} must be a nonnegative Integer" unless option_value.is_a?(Integer) and option_value >= 0 # Declare different validations per option. validity_checks = { :is => "==", :minimum => ">=", :maximum => "<=" } = { :is => :wrong_length, :minimum => :too_short, :maximum => :too_long } = ([:message] || [[option]]) % option_value validates_each(attrs, ) do |record, attr, value| if value.kind_of?(String) record.errors.add(attr, ) unless !value.nil? and value.split(//).size.method(validity_checks[option])[option_value] else record.errors.add(attr, ) unless !value.nil? and value.size.method(validity_checks[option])[option_value] end end end end |
#validates_numericality_of(*attr_names) ⇒ Object
Validates whether the value of the specified attribute is numeric by trying to convert it to a float with Kernel.Float (if integer
is false) or applying it to the regular expression /\A[+\-]?\d+\Z/
(if integer
is set to true).
class Person < ActiveRecord::Base
validates_numericality_of :value, :on => :create
end
Configuration options:
-
message
- A custom error message (default is: “is not a number”) -
on
Specifies when this validation is active (default is :save, other options :create, :update) -
only_integer
Specifies whether the value has to be an integer, e.g. an integral value (default is false) -
allow_nil
Skip validation if attribute is nil (default is false). Notice that for fixnum and float columns empty strings are converted to nil -
greater_than
Specifies the value must be greater than the supplied value -
greater_than_or_equal_to
Specifies the value must be greater than or equal the supplied value -
equal_to
Specifies the value must be equal to the supplied value -
less_than
Specifies the value must be less than the supplied value -
less_than_or_equal_to
Specifies the value must be less than or equal the supplied value -
odd
Specifies the value must be an odd number -
even
Specifies the value must be an even number -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 827 def validates_numericality_of(*attr_names) configuration = { :on => :save, :only_integer => false, :allow_nil => false } configuration.update(attr_names.) = ALL_NUMERICALITY_CHECKS.keys & configuration.keys ( - [ :odd, :even ]).each do |option| raise ArgumentError, ":#{option} must be a number" unless configuration[option].is_a?(Numeric) end validates_each(attr_names,configuration) do |record, attr_name, value| raw_value = record.send("#{attr_name}_before_type_cast") || value next if configuration[:allow_nil] and raw_value.nil? if configuration[:only_integer] unless raw_value.to_s =~ /\A[+-]?\d+\Z/ record.errors.add(attr_name, configuration[:message] || ActiveRecord::Errors.[:not_a_number]) next end raw_value = raw_value.to_i else begin raw_value = Kernel.Float(raw_value.to_s) rescue ArgumentError, TypeError record.errors.add(attr_name, configuration[:message] || ActiveRecord::Errors.[:not_a_number]) next end end .each do |option| case option when :odd, :even record.errors.add(attr_name, configuration[:message] || ActiveRecord::Errors.[option]) unless raw_value.to_i.method(ALL_NUMERICALITY_CHECKS[option])[] else record.errors.add(attr_name, configuration[:message] || (ActiveRecord::Errors.[option] % configuration[option])) unless raw_value.method(ALL_NUMERICALITY_CHECKS[option])[configuration[option]] end end end end |
#validates_presence_of(*attr_names) ⇒ Object
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:
-
message
- A custom error message (default is: “can’t be blank”) -
on
- Specifies when this validation is active (default is :save, other options :create, :update) -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
Warning
Validate the presence of the foreign key, not the instance variable itself. Do this:
validates_presence_of :invoice_id
Not this:
validates_presence_of :invoice
If you validate the presence of the associated object, you will get failures on saves when both the parent object and the child object are new.
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# File 'lib/active_record/validations.rb', line 479 def validates_presence_of(*attr_names) configuration = { :message => ActiveRecord::Errors.[:blank], :on => :save } configuration.update(attr_names.) # can't use validates_each here, because it cannot cope with nonexistent attributes, # while errors.add_on_empty can send(validation_method(configuration[:on])) do |record| unless (configuration[:if] && !evaluate_condition(configuration[:if], record)) || (configuration[:unless] && evaluate_condition(configuration[:unless], record)) record.errors.add_on_blank(attr_names, configuration[:message]) end end end |
#validates_uniqueness_of(*attr_names) ⇒ Object
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.
Because this check is performed outside the database there is still a chance that duplicate values will be inserted in two parallel transactions. To guarantee against this you should create a unique index on the field. See create_index
for more information.
Configuration options:
-
message
- Specifies a custom error message (default is: “has already been taken”) -
scope
- One or more columns by which to limit the scope of the uniquness constraint. -
case_sensitive
- Looks for an exact match. Ignored by non-text columns (true by default). -
allow_nil
- If set to true, skips this validation if the attribute is null (default is: false) -
allow_blank
- If set to true, skips this validation if the attribute is blank (default is: false) -
if
- Specifies a method, proc or string to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value. -
unless
- Specifies a method, proc or string to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or string should return or evaluate to a true or false value.
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# File 'lib/active_record/validations.rb', line 617 def validates_uniqueness_of(*attr_names) configuration = { :message => ActiveRecord::Errors.[:taken], :case_sensitive => true } configuration.update(attr_names.) validates_each(attr_names,configuration) do |record, attr_name, value| if value.nil? || (configuration[:case_sensitive] || !columns_hash[attr_name.to_s].text?) condition_sql = "#{record.class.table_name}.#{attr_name} #{attribute_condition(value)}" condition_params = [value] else condition_sql = "LOWER(#{record.class.table_name}.#{attr_name}) #{attribute_condition(value)}" condition_params = [value.downcase] end if scope = configuration[:scope] Array(scope).map do |scope_item| scope_value = record.send(scope_item) condition_sql << " AND #{record.class.table_name}.#{scope_item} #{attribute_condition(scope_value)}" condition_params << scope_value end end unless record.new_record? condition_sql << " AND #{record.class.table_name}.#{record.class.primary_key} <> ?" condition_params << record.send(:id) end # The check for an existing value should be run from a class that # isn't abstract. This means working down from the current class # (self), to the first non-abstract class. Since classes don't know # their subclasses, we have to build the hierarchy between self and # the record's class. class_hierarchy = [record.class] while class_hierarchy.first != self class_hierarchy.insert(0, class_hierarchy.first.superclass) end # Now we can work our way down the tree to the first non-abstract # class (which has a database table to query from). finder_class = class_hierarchy.detect { |klass| !klass.abstract_class? } if finder_class.find(:first, :conditions => [condition_sql, *condition_params]) record.errors.add(attr_name, configuration[:message]) end end end |