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rails--rails/activemodel/lib/active_model/validator.rb

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module ActiveModel #:nodoc:
# 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[: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 <tt>validate</tt> which accepts a <tt>record</tt>.
#
# class Person
# include ActiveModel::Validations
# validates_with MyValidator
# end
#
# class MyValidator < ActiveModel::Validator
# def validate
# 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 <tt>record<tt>'s errors directly
# from within the validators message
#
# class MyValidator < ActiveModel::Validator
# def validate(record)
# record.errors[:base] << "This is some custom error message"
# record.errors[: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(record, options)
# super
# @my_custom_field = options[:field_name] || :first_name
# end
# end
#
# The easiest way to add custom validators for validating individual attributes
# is with the convenient ActiveModel::EachValidator for example:
#
# class TitleValidator < ActiveModel::EachValidator
# def validate_each(record, attribute, value)
# record.errors[attribute] << 'must be Mr. Mrs. or Dr.' unless ['Mr.', 'Mrs.', 'Dr.'].include?(value)
# end
# end
#
# This can now be used in combination with the +validates+ method
# (see ActiveModel::Validations::ClassMethods.validates for more on this)
#
# class Person
# include ActiveModel::Validations
# attr_accessor :title
#
# validates :title, :presence => true, :title => true
# end
#
# Validator may also define a +setup+ instance method which will get called
# with the class that using that validator as it's argument. This can be
# useful when there are prerequisites such as an attr_accessor being present
# for example:
#
# class MyValidator < ActiveModel::Validator
# def setup(klass)
# klass.send :attr_accessor, :custom_attribute
# end
# end
#
class Validator
attr_reader :options
# Accepts options that will be made availible through the +options+ reader.
def initialize(options)
@options = options
end
# Override this method in subclasses with validation logic, adding errors
# to the records +errors+ array where necessary.
def validate(record)
raise NotImplementedError
end
end
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# EachValidator is a validator which iterates through the attributes given
# in the options hash invoking the validate_each method passing in the
# record, attribute and value.
#
# All ActiveModel validations are built on top of this Validator.
class EachValidator < Validator
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)
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@attributes = Array(options.delete(:attributes))
raise ":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.
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def validate_each(record, attribute, value)
raise NotImplementedError
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
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# 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
def initialize(options, &block)
@block = block
super
end
private
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def validate_each(record, attribute, value)
@block.call(record, attribute, value)
end
end
end