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require "active_support/core_ext/module/anonymous"
module ActiveModel
# == Active \Model \Validator
#
# A simple base class that can be used along with
# ActiveModel::Validations::ClassMethods.validates_with
#
# class Person
# include ActiveModel::Validations
# validates_with MyValidator
# end
#
# class MyValidator < ActiveModel::Validator
# def validate(record)
# if some_complex_logic
# record.errors.add(:base, "This record is invalid")
# end
# end
#
# private
# def some_complex_logic
# # ...
# end
# end
#
# Any class that inherits from ActiveModel::Validator must implement a method
# called +validate+ which accepts a +record+.
#
# class Person
# include ActiveModel::Validations
# validates_with MyValidator
# end
#
# class MyValidator < ActiveModel::Validator
# def validate(record)
# record # => The person instance being validated
# options # => Any non-standard options passed to validates_with
# end
# end
#
# To cause a validation error, you must add to the +record+'s errors directly
# from within the validators message.
#
# class MyValidator < ActiveModel::Validator
# def validate(record)
# record.errors.add :base, "This is some custom error message"
# record.errors.add :first_name, "This is some complex validation"
# # etc...
# end
# end
#
# To add behavior to the initialize method, use the following signature:
#
# class MyValidator < ActiveModel::Validator
# def initialize(options)
# super
# @my_custom_field = options[:field_name] || :first_name
# end
# end
#
# Note that the validator is initialized only once for the whole application
# life cycle, and not on each validation run.
#
# The easiest way to add custom validators for validating individual attributes
# is with the convenient <tt>ActiveModel::EachValidator</tt>.
#
# class TitleValidator < ActiveModel::EachValidator
# def validate_each(record, attribute, value)
# record.errors.add attribute, 'must be Mr., Mrs., or Dr.' unless %w(Mr. Mrs. Dr.).include?(value)
# end
# end
#
# This can now be used in combination with the +validates+ method
# (see <tt>ActiveModel::Validations::ClassMethods.validates</tt> for more on this).
#
# class Person
# include ActiveModel::Validations
# attr_accessor :title
#
# validates :title, presence: true, title: true
# end
#
# It can be useful to access the class that is using that validator when there are prerequisites such
# as an +attr_accessor+ being present. This class is accessible via +options[:class]+ in the constructor.
# To setup your validator override the constructor.
#
# class MyValidator < ActiveModel::Validator
# def initialize(options={})
# super
# options[:class].send :attr_accessor, :custom_attribute
# end
# end
class Validator
attr_reader :options
# Returns the kind of the validator.
#
# PresenceValidator.kind # => :presence
# UniquenessValidator.kind # => :uniqueness
def self.kind
@kind ||= name.split("::").last.underscore.chomp("_validator").to_sym unless anonymous?
end
# Accepts options that will be made available through the +options+ reader.
def initialize(options = {})
@options = options.except(:class).freeze
end
# Returns the kind for this validator.
#
# PresenceValidator.new.kind # => :presence
# UniquenessValidator.new.kind # => :uniqueness
def kind
self.class.kind
end
# Override this method in subclasses with validation logic, adding errors
# to the records +errors+ array where necessary.
def validate(record)
raise NotImplementedError, "Subclasses must implement a validate(record) method."
end
end
# +EachValidator+ is a validator which iterates through the attributes given
# in the options hash invoking the <tt>validate_each</tt> method passing in the
# record, attribute and value.
#
# All \Active \Model validations are built on top of this validator.
class EachValidator < Validator #:nodoc:
attr_reader :attributes
# Returns a new validator instance. All options will be available via the
# +options+ reader, however the <tt>:attributes</tt> option will be removed
# and instead be made available through the +attributes+ reader.
def initialize(options)
@attributes = Array(options.delete(:attributes))
raise ArgumentError, ":attributes cannot be blank" if @attributes.empty?
super
check_validity!
end
# Performs validation on the supplied record. By default this will call
# +validates_each+ to determine validity therefore subclasses should
# override +validates_each+ with validation logic.
def validate(record)
attributes.each do |attribute|
value = record.read_attribute_for_validation(attribute)
next if (value.nil? && options[:allow_nil]) || (value.blank? && options[:allow_blank])
validate_each(record, attribute, value)
end
end
# Override this method in subclasses with the validation logic, adding
# errors to the records +errors+ array where necessary.
def validate_each(record, attribute, value)
raise NotImplementedError, "Subclasses must implement a validate_each(record, attribute, value) method"
end
# Hook method that gets called by the initializer allowing verification
# that the arguments supplied are valid. You could for example raise an
# +ArgumentError+ when invalid options are supplied.
def check_validity!
end
end
# +BlockValidator+ is a special +EachValidator+ which receives a block on initialization
# and call this block for each attribute being validated. +validates_each+ uses this validator.
class BlockValidator < EachValidator #:nodoc:
def initialize(options, &block)
@block = block
super
end
private
def validate_each(record, attribute, value)
@block.call(record, attribute, value)
end
end
end
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