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Introduce validates_with to encapsulate attribute validations in a cl…
…ass.

[#2630 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>
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zilkey authored and jeremy committed Aug 10, 2009
1 parent 7975885 commit 22f3398
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5 changes: 5 additions & 0 deletions activemodel/CHANGELOG
@@ -0,0 +1,5 @@
*Edge*

* Introduce validates_with to encapsulate attribute validations in a class. #2630 [Jeff Dean]

* Extracted from Active Record and Active Resource.
2 changes: 1 addition & 1 deletion activemodel/CHANGES
Expand Up @@ -9,4 +9,4 @@ Changes from extracting bits to ActiveModel
klass.add_observer(self)
klass.class_eval 'def after_find() end' unless
klass.respond_to?(:after_find)
end
end
64 changes: 64 additions & 0 deletions activemodel/lib/active_model/validations/with.rb
@@ -0,0 +1,64 @@
module ActiveModel
module Validations
module ClassMethods

# Passes the record off to the class or classes specified and allows them to add errors based on more complex conditions.
#
# class Person < ActiveRecord::Base
# validates_with MyValidator
# end
#
# class MyValidator < ActiveRecord::Validator
# def validate
# if some_complex_logic
# record.errors[:base] << "This record is invalid"
# end
# end
#
# private
# def some_complex_logic
# # ...
# end
# end
#
# You may also pass it multiple classes, like so:
#
# class Person < ActiveRecord::Base
# validates_with MyValidator, MyOtherValidator, :on => :create
# end
#
# Configuration options:
# * <tt>on</tt> - Specifies when this validation is active (<tt>:create</tt> or <tt>:update</tt>
# * <tt>if</tt> - Specifies a method, proc or string to call to determine if the validation should
# occur (e.g. <tt>:if => :allow_validation</tt>, or <tt>:if => Proc.new { |user| user.signup_step > 2 }</tt>).
# The method, proc or string should return or evaluate to a true or false value.
# * <tt>unless</tt> - Specifies a method, proc or string to call to determine if the validation should
# not occur (e.g. <tt>:unless => :skip_validation</tt>, or <tt>:unless => Proc.new { |user| user.signup_step <= 2 }</tt>).
# The method, proc or string should return or evaluate to a true or false value.
#
# If you pass any additional configuration options, they will be passed to the class and available as <tt>options</tt>:
#
# class Person < ActiveRecord::Base
# validates_with MyValidator, :my_custom_key => "my custom value"
# end
#
# class MyValidator < ActiveRecord::Validator
# def validate
# options[:my_custom_key] # => "my custom value"
# end
# end
#
def validates_with(*args)
configuration = args.extract_options!

send(validation_method(configuration[:on]), configuration) do |record|
args.each do |klass|
klass.new(record, configuration.except(:on, :if, :unless)).validate
end
end
end
end
end
end


116 changes: 116 additions & 0 deletions activemodel/test/cases/validations/with_validation_test.rb
@@ -0,0 +1,116 @@
# encoding: utf-8
require 'cases/helper'

require 'models/topic'

class ValidatesWithTest < ActiveRecord::TestCase
include ActiveModel::ValidationsRepairHelper

repair_validations(Topic)

ERROR_MESSAGE = "Validation error from validator"
OTHER_ERROR_MESSAGE = "Validation error from other validator"

class ValidatorThatAddsErrors < ActiveRecord::Validator
def validate()
record.errors[:base] << ERROR_MESSAGE
end
end

class OtherValidatorThatAddsErrors < ActiveRecord::Validator
def validate()
record.errors[:base] << OTHER_ERROR_MESSAGE
end
end

class ValidatorThatDoesNotAddErrors < ActiveRecord::Validator
def validate()
end
end

class ValidatorThatValidatesOptions < ActiveRecord::Validator
def validate()
if options[:field] == :first_name
record.errors[:base] << ERROR_MESSAGE
end
end
end

test "vaidation with class that adds errors" do
Topic.validates_with(ValidatorThatAddsErrors)
topic = Topic.new
assert !topic.valid?, "A class that adds errors causes the record to be invalid"
assert topic.errors[:base].include?(ERROR_MESSAGE)
end

test "with a class that returns valid" do
Topic.validates_with(ValidatorThatDoesNotAddErrors)
topic = Topic.new
assert topic.valid?, "A class that does not add errors does not cause the record to be invalid"
end

test "with a class that adds errors on update and a new record" do
Topic.validates_with(ValidatorThatAddsErrors, :on => :update)
topic = Topic.new
assert topic.valid?, "Validation doesn't run on create if 'on' is set to update"
end

test "with a class that adds errors on create and a new record" do
Topic.validates_with(ValidatorThatAddsErrors, :on => :create)
topic = Topic.new
assert !topic.valid?, "Validation does run on create if 'on' is set to create"
assert topic.errors[:base].include?(ERROR_MESSAGE)
end

test "with multiple classes" do
Topic.validates_with(ValidatorThatAddsErrors, OtherValidatorThatAddsErrors)
topic = Topic.new
assert !topic.valid?
assert topic.errors[:base].include?(ERROR_MESSAGE)
assert topic.errors[:base].include?(OTHER_ERROR_MESSAGE)
end

test "with if statements that return false" do
Topic.validates_with(ValidatorThatAddsErrors, :if => "1 == 2")
topic = Topic.new
assert topic.valid?
end

test "with if statements that return true" do
Topic.validates_with(ValidatorThatAddsErrors, :if => "1 == 1")
topic = Topic.new
assert !topic.valid?
assert topic.errors[:base].include?(ERROR_MESSAGE)
end

test "with unless statements that return true" do
Topic.validates_with(ValidatorThatAddsErrors, :unless => "1 == 1")
topic = Topic.new
assert topic.valid?
end

test "with unless statements that returns false" do
Topic.validates_with(ValidatorThatAddsErrors, :unless => "1 == 2")
topic = Topic.new
assert !topic.valid?
assert topic.errors[:base].include?(ERROR_MESSAGE)
end

test "passes all non-standard configuration options to the validator class" do
topic = Topic.new
validator = mock()
validator.expects(:new).with(topic, {:foo => :bar}).returns(validator)
validator.expects(:validate)

Topic.validates_with(validator, :if => "1 == 1", :foo => :bar)
assert topic.valid?
end

test "validates_with with options" do
Topic.validates_with(ValidatorThatValidatesOptions, :field => :first_name)
topic = Topic.new
assert !topic.valid?
assert topic.errors[:base].include?(ERROR_MESSAGE)
end

end
1 change: 1 addition & 0 deletions activerecord/lib/active_record.rb
Expand Up @@ -69,6 +69,7 @@ def self.load_all!
autoload :TestCase, 'active_record/test_case'
autoload :Timestamp, 'active_record/timestamp'
autoload :Transactions, 'active_record/transactions'
autoload :Validator, 'active_record/validator'
autoload :Validations, 'active_record/validations'

module AttributeMethods
Expand Down
68 changes: 68 additions & 0 deletions activerecord/lib/active_record/validator.rb
@@ -0,0 +1,68 @@
module ActiveRecord #:nodoc:

# A simple base class that can be used along with ActiveRecord::Base.validates_with
#
# class Person < ActiveRecord::Base
# validates_with MyValidator
# end
#
# class MyValidator < ActiveRecord::Validator
# def validate
# 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 ActiveRecord::Validator will have access to <tt>record</tt>,
# which is an instance of the record being validated, and must implement a method called <tt>validate</tt>.
#
# class Person < ActiveRecord::Base
# validates_with MyValidator
# end
#
# class MyValidator < ActiveRecord::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 < ActiveRecord::Validator
# def validate
# 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 < ActiveRecord::Validator
# def initialize(record, options)
# super
# @my_custom_field = options[:field_name] || :first_name
# end
# end
#
class Validator
attr_reader :record, :options

def initialize(record, options)
@record = record
@options = options
end

def validate
raise "You must override this method"
end
end
end

3 comments on commit 22f3398

@adzap
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@adzap adzap commented on 22f3398 Aug 10, 2009

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This is a great addition, but given it introduces the Validator class could not all ActiveModel validations defined in terms a of validator class? I am thinking of the Merb style of validation.

@conradwt
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Where should one install their Validator class(es)?

@zilkey
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@zilkey zilkey commented on 22f3398 Aug 14, 2009

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I alternate between putting validator classes in app/models (for small apps) or in a separate app/validators directory, and adding that directory to the load path in environment.rb.

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