Lotus::Validations

Validations mixins for objects

Status

Contact

• Home page: http://lotusrb.org
• Mailing List: http://lotusrb.org/mailing-list
• API Doc: http://rdoc.info/gems/lotus-validations
• Bugs/Issues: https://github.com/lotus/validations/issues
• Support: http://stackoverflow.com/questions/tagged/lotus-ruby
• Chat: https://gitter.im/lotus/chat

Rubies

Lotus::Validations supports Ruby (MRI) 2+, JRuby 9k+ & Rubinius 2.3+

Installation

Add this line to your application's Gemfile:

gem 'lotus-validations'

And then execute:

$ bundle

Or install it yourself as:

$ gem install lotus-validations

Usage

Lotus::Validations is a set of lightweight validations for Ruby objects.

Attributes

The framework allows you to define attributes for each object.

It defines an initializer, whose attributes can be passed as a hash. All unknown values are ignored, which is useful for whitelisting attributes.

require 'lotus/validations'

class Person
  include Lotus::Validations

  attribute :name,  presence: true
  attribute :email, presence: true
end

person = Person.new(name: 'Luca', email: 'me@example.org', age: 32)
person.name  # => "Luca"
person.email # => "me@example.org"
person.age   # => raises NoMethodError because `:age` wasn't defined as attribute.

Blank Values

The framework will treat as valid any blank attributes, without presence, for both format and size predicates.

require 'lotus/validations'

class Person
  include Lotus::Validations

  attribute :name,    type: String, size: 5..45
  attribute :email,   type: String, size: 20..80, format: /@/
  attribute :skills,  type: Array,  size: 1..3
  attribute :keys,    type: Hash,   size: 1..3
end

Person.new.valid?                             # < true
Person.new(name: '').valid?                   # < true
Person.new(skills: '').valid?                 # < true
Person.new(skills: ['ruby', 'lotus']).valid?  # < true

Person.new(skills: []).valid?                 # < false
Person.new(keys: {}).valid?                   # < false
Person.new(keys: {a: :b}, skills: []).valid?  # < false

If you want to disable this behaviour, please, refer to presence.

Validations

If you prefer Lotus::Validations to only define validations, but not attributes, you can use the following alternative syntax.

require 'lotus/validations'

class Person
  include Lotus::Validations
  attr_accessor :name, :email

  # Custom initializer
  def initialize(attributes = {})
    @name, @email = attributes.values_at(:name, :email)
  end

  validates :name,  presence: true
  validates :email, presence: true
end

person = Person.new(name: 'Luca', email: 'me@example.org')
person.name  # => "Luca"
person.email # => "me@example.org"

This is a bit more verbose, but offers a great level of flexibility for your Ruby objects. It also allows to use Lotus::Validations in combination with other frameworks.

Coercions

If a Ruby class is passed to the :type option, the given value is coerced, accordingly.

Standard coercions

require 'lotus/validations'

class Person
  include Lotus::Validations

  attribute :fav_number, type: Integer
end

person = Person.new(fav_number: '23')
person.valid?

person.fav_number # => 23

Allowed types are:

• Array
• BigDecimal
• Boolean
• Date
• DateTime
• Float
• Hash
• Integer
• Pathname
• Set
• String
• Symbol
• Time

Custom coercions

If a user defined class is specified, it can be freely used for coercion purposes. The only limitation is that the constructor should have arity of 1.

require 'lotus/validations'

class FavNumber
  def initialize(number)
    @number = number
  end
end

class BirthDate
end

class Person
  include Lotus::Validations

  attribute :fav_number, type: FavNumber
  attribute :date,       type: BirthDate
end

person = Person.new(fav_number: '23', date: 'Oct 23, 2014')
person.valid?

person.fav_number # => #<FavNumber:0x007ffc644bba00 @number="23">
person.date       # => this raises an error, because BirthDate#initialize doesn't accept any arg

Validations

Each attribute definition can receive a set of options to define one or more validations.

Validations are triggered when you invoke #valid?.

Acceptance

An attribute is valid if its value is truthy.

require 'lotus/validations'

class Signup
  include Lotus::Validations

  attribute :terms_of_service, acceptance: true
end

signup = Signup.new(terms_of_service: '1')
signup.valid? # => true

signup = Signup.new(terms_of_service: 'true')
signup.valid? # => true

signup = Signup.new(terms_of_service: '')
signup.valid? # => false

signup = Signup.new(terms_of_service: '0')
signup.valid? # => false

Confirmation

An attribute is valid if its value and the value of a corresponding attribute is valid.

By convention, if you have a password attribute, the validation looks for password_confirmation.

require 'lotus/validations'

class Signup
  include Lotus::Validations

  attribute :password, confirmation: true
end

signup = Signup.new(password: 'secret', password_confirmation: 'secret')
signup.valid? # => true

signup = Signup.new(password: 'secret', password_confirmation: 'x')
signup.valid? # => false

Exclusion

An attribute is valid, if the value isn't excluded from the value described by the validator.

The validator value can be anything that responds to #include?. In Ruby, this includes most of the core objects: String, Enumerable (Array, Hash, Range, Set).

See also Inclusion.

require 'lotus/validations'

class Signup
  include Lotus::Validations

  attribute :music, exclusion: ['pop']
end

signup = Signup.new(music: 'rock')
signup.valid? # => true

signup = Signup.new(music: 'pop')
signup.valid? # => false

Format

An attribute is valid if it matches the given Regular Expression.

require 'lotus/validations'

class Signup
  include Lotus::Validations

  attribute :name, format: /\A[a-zA-Z]+\z/
end

signup = Signup.new(name: 'Luca')
signup.valid? # => true

signup = Signup.new(name: '23')
signup.valid? # => false

Inclusion

An attribute is valid, if the value provided is included in the validator's value.

The validator value can be anything that responds to #include?. In Ruby, this includes most of the core objects: like String, Enumerable (Array, Hash, Range, Set).

See also Exclusion.

require 'prime'
require 'lotus/validations'

class PrimeNumbers
  def initialize(limit)
    @numbers = Prime.each(limit).to_a
  end

  def include?(number)
    @numbers.include?(number)
  end
end

class Signup
  include Lotus::Validations

  attribute :age,        inclusion: 18..99
  attribute :fav_number, inclusion: PrimeNumbers.new(100)
end

signup = Signup.new(age: 32)
signup.valid? # => true

signup = Signup.new(age: 17)
signup.valid? # => false

signup = Signup.new(fav_number: 23)
signup.valid? # => true

signup = Signup.new(fav_number: 8)
signup.valid? # => false

Presence

An attribute is valid if present.

require 'lotus/validations'

class Signup
  include Lotus::Validations

  attribute :name, presence: true
end

signup = Signup.new(name: 'Luca')
signup.valid? # => true

signup = Signup.new(name: '')
signup.valid? # => false

signup = Signup.new(name: nil)
signup.valid? # => false

Size

An attribute is valid if its #size falls within the described value.

require 'lotus/validations'

class Signup
  MEGABYTE = 1024 ** 2
  include Lotus::Validations

  attribute :ssn,      size: 11    # exact match
  attribute :password, size: 8..64 # range
  attribute :avatar,   size: 1..(5 * MEGABYTE)
end

signup = Signup.new(password: 'a-very-long-password')
signup.valid? # => true

signup = Signup.new(password: 'short')
signup.valid? # => false

Note that in the example above you are able to validate the weight of the file, because Ruby's File and Tempfile both respond to #size.

Uniqueness

Uniqueness validations aren't implemented because this library doesn't deal with persistence. The other reason is that this isn't an effective way to ensure uniqueness of a value in a database.

Please read more at: The Perils of Uniqueness Validations.

Nested validations

Nested validations are handled with a nested block syntax.

class ShippingDetails
  include Lotus::Validations

  attribute :full_name, presence: true

  attribute :address do
    attribute :street,      presence: true
    attribute :city,        presence: true
    attribute :country,     presence: true
    attribute :postal_code, presence: true, format: /.../
  end
end

validator = ShippingDetails.new
validator.valid? # => false

Bulk operations on errors are guaranteed by #each. This method yields a flattened collection of errors.

validator.errors.each do |error|
  error.name
    # => on the first iteration it returns "full_name"
    # => the second time it returns "address.street" and so on..
end

Errors for a specific attribute can be accessed via #for.

error = validator.errors.for('full_name').first
error.name           # => "full_name"
error.attribute_name # => "full_name"

error = validator.errors.for('address.street').first
error.name           # => "address.street"
error.attribute_name # => "street"

Composable validations

Validations can be reused via composition:

require 'lotus/validations'

module NameValidations
  include Lotus::Validations

  attribute :name, presence: true
end

module EmailValidations
  include Lotus::Validations

  attribute :email, presence: true, format: /.../
end

module PasswordValidations
  include Lotus::Validations

  # We validate only the presence here
  attribute :password, presence: true
end

module CommonValidations
  include EmailValidations
  include PasswordValidations
end

# A valid signup requires:
#   * name (presence)
#   * email (presence and format)
#   * password (presence and confirmation)
class Signup
  include NameValidations
  include CommonValidations

  # We decorate PasswordValidations behavior, by requiring the confirmation too.
  # This additional validation is active only in this case.
  attribute :password, confirmation: true
end

# A valid signin requires:
#   * email (presence)
#   * password (presence)
class Signin
  include CommonValidations
end

# A valid "forgot password" requires:
#   * email (presence)
class ForgotPassword
  include EmailValidations
end

Complete example

require 'lotus/validations'

class Signup
  include Lotus::Validations

  attribute :first_name, presence: true
  attribute :last_name,  presence: true
  attribute :email,      presence: true, format: /\A(.*)@(.*)\.(.*)\z/
  attribute :password,   presence: true, confirmation: true, size: 8..64
end

Errors

When you invoke #valid?, validation errors are available at #errors. It's a set of errors grouped by attribute. Each error contains the name of the invalid attribute, the failed validation, the expected value, and the current one.

require 'lotus/validations'

class Signup
  include Lotus::Validations

  attribute :email, presence: true, format: /\A(.*)@(.*)\.(.*)\z/
  attribute :age, size: 18..99
end

signup = Signup.new(email: 'user@example.org')
signup.valid? # => true

signup = Signup.new(email: '', age: 17)
signup.valid? # => false

signup.errors
  # => #<Lotus::Validations::Errors:0x007fe00ced9b78
  # @errors={
  #   :email=>[
  #     #<Lotus::Validations::Error:0x007fe00cee3290 @attribute=:email, @validation=:presence, @expected=true, @actual="">,
  #     #<Lotus::Validations::Error:0x007fe00cee31f0 @attribute=:email, @validation=:format, @expected=/\A(.*)@(.*)\.(.*)\z/, @actual="">
  #   ],
  #   :age=>[
  #     #<Lotus::Validations::Error:0x007fe00cee30d8 @attribute=:age, @validation=:size, @expected=18..99, @actual=17>
  #   ]
  # }>

Lotus::Entity

Integration with Lotus::Entity is straight forward.

require 'lotus/model'
require 'lotus/validations'

class Product
  include Lotus::Entity
  include Lotus::Validations

  attribute :name,  type: String,  presence: true
  attribute :price, type: Integer, presence: true
end

product = Product.new(name: 'Book', price: '100')
product.valid? # => true

product.name  # => "Book"
product.price # => 100

Contributing

1. Fork it ( https://github.com/lotus/lotus-validations/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Copyright

Copyright © 2014-2016 Luca Guidi – Released under MIT License