Is called before valid? or valid_for_*?

  class Person
    include Validatable
    before_validation do
      self.name = "default name"
    end

    attr_accessor :name
  end

[Source]

     # File lib/macros.rb, line 279
279:     def before_validation(&block)
280:       before_validations << block
281:     end

Validates the specified attributes.

  class Person
    include Validatable
    validates_presence_of :name
    attr_accessor :name
  end

  class PersonPresenter
    include Validatable
    include_errors_from :person, :map => { :name => :namen }, :if => lambda { not person.nil? }
    attr_accessor :person

    def initialize(person)
      @person = person
    end
  end

  presenter = PersonPresenter.new(Person.new)
  presenter.valid? #=> false
  presenter.errors.on(:namen) #=> "can't be blank"

The person attribute will be validated. If person is invalid the errors will be added to the PersonPresenter errors collection.

Configuration options:

    * map - A hash that maps attributes of the child to attributes of the parent.
    * if - A block that when executed must return true of the validation will not occur.

[Source]

     # File lib/macros.rb, line 257
257:     def include_errors_from(attribute_to_validate, options = {})
258:       children_to_validate << ChildValidation.new(attribute_to_validate, options[:map] || {}, options[:if] || lambda { true })
259:     end

Includes all the validations that are defined on the attribute.

  class Person
    include Validatable
    validates_presence_of :name
  end

  class PersonPresenter
    include Validatable
    include_validataions_from :person
    attr_accessor :person
    def name
      person.name
    end

    def initialize(person)
      @person = person
    end
  end

  presenter = PersonPresenter.new(Person.new)
  presenter.valid? #=> false
  presenter.errors.on(:name) #=> "can't be blank"

The name attribute whose validations should be added.

[Source]

     # File lib/macros.rb, line 223
223:     def include_validations_from(attribute_to_validate, options = {})
224:       validations_to_include << IncludedValidation.new(attribute_to_validate)
225:     end

Encapsulates the pattern of wanting to validate the acceptance of a terms of service check box (or similar agreement). Example:

  class Person
    include Validatable
    validates_acceptance_of :terms_of_service
    validates_acceptance_of :eula, :message => "must be abided"
  end

Configuration options:

    * after_validate - A block that executes following the run of a validation
    * message - The message to add to the errors collection when the validation fails
    * times - The number of times the validation applies
    * level - The level at which the validation should occur
    * if - A block that when executed must return true of the validation will not occur
    * group - The group that this validation belongs to.  A validation can belong to multiple groups

[Source]

     # File lib/macros.rb, line 118
118:     def validates_acceptance_of(*args)
119:       add_validations(args, ValidatesAcceptanceOf)
120:     end

Encapsulates the pattern of wanting to validate a password or email address field with a confirmation. Example:

  Class:
    class PersonPresenter
      include Validatable
      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" %>

Configuration options:

    * after_validate - A block that executes following the run of a validation
    * case_sensitive - Whether or not to apply case-sensitivity on the comparison.  Defaults to true.
    * message - The message to add to the errors collection when the validation fails
    * times - The number of times the validation applies
    * level - The level at which the validation should occur
    * if - A block that when executed must return true of the validation will not occur
    * group - The group that this validation belongs to.  A validation can belong to multiple groups

[Source]

     # File lib/macros.rb, line 146
146:     def validates_confirmation_of(*args)
147:       add_validations(args, ValidatesConfirmationOf)
148:     end

Validates that the logic evaluates to true

  class Address
    include Validatable
    validates_each :zip_code, :logic => lambda { errors.add(:zip_code, "is not valid") if ZipCodeService.allows(zip_code) }
  end

The logic option is required.

Configuration options:

    * after_validate - A block that executes following the run of a validation
    * group - The group that this validation belongs to.  A validation can belong to multiple groups
    * if - A block that when executed must return true of the validation will not occur
    * level - The level at which the validation should occur
    * logic - A block that executes to perform the validation
    * message - The message to add to the errors collection when the validation fails
    * times - The number of times the validation applies

[Source]

    # File lib/macros.rb, line 23
23:     def validates_each(*args)
24:       add_validations(args, ValidatesEach)
25:     end

Validates whether the value of the specified attribute is of the correct form by matching it against the regular expression provided.

  class Person
    include Validatable
    validates_format_of :first_name, :with => /[ A-Za-z]/
  end

A regular expression must be provided or else an exception will be raised.

Configuration options:

    * after_validate - A block that executes following the run of a validation
    * message - The message to add to the errors collection when the validation fails
    * times - The number of times the validation applies
    * level - The level at which the validation should occur
    * if - A block that when executed must return true of the validation will not occur
    * with - The regular expression used to validate the format
    * group - The group that this validation belongs to.  A validation can belong to multiple groups

[Source]

    # File lib/macros.rb, line 48
48:     def validates_format_of(*args)
49:       add_validations(args, ValidatesFormatOf)
50:     end

Validates that the specified attribute matches the length restrictions supplied.

  class Person
    include Validatable
    validates_length_of :first_name, :maximum=>30
    validates_length_of :last_name, :minimum=>30
  end

Configuration options:

    * after_validate - A block that executes following the run of a validation
    * message - The message to add to the errors collection when the validation fails
    * times - The number of times the validation applies
    * level - The level at which the validation should occur
    * if - A block that when executed must return true of the validation will not occur
    * minimum - The minimum size of the attribute
    * maximum - The maximum size of the attribute
    * is - The size the attribute must be
    * within - A range that the size of the attribute must fall within
    * group - The group that this validation belongs to.  A validation can belong to multiple groups

[Source]

    # File lib/macros.rb, line 74
74:     def validates_length_of(*args)
75:       add_validations(args, ValidatesLengthOf)
76:     end

Validates that the specified attribute is numeric.

  class Person
    include Validatable
    validates_numericality_of :age
  end

Configuration options:

    * after_validate - A block that executes following the run of a validation
    * message - The message to add to the errors collection when the validation fails
    * times - The number of times the validation applies
    * level - The level at which the validation should occur
    * if - A block that when executed must return true of the validation will not occur
    * group - The group that this validation belongs to.  A validation can belong to multiple groups
    * only_integer - Whether the attribute must be an integer (default is false)

[Source]

    # File lib/macros.rb, line 96
96:     def validates_numericality_of(*args)
97:       add_validations(args, ValidatesNumericalityOf)
98:     end

Validates that the specified attributes are not nil or an empty string

  class Person
    include Validatable
    validates_presence_of :first_name
  end

The first_name attribute must be in the object and it cannot be nil or empty.

Configuration options:

    * after_validate - A block that executes following the run of a validation
    * message - The message to add to the errors collection when the validation fails
    * times - The number of times the validation applies
    * level - The level at which the validation should occur
    * if - A block that when executed must return true of the validation will not occur
    * group - The group that this validation belongs to.  A validation can belong to multiple groups

[Source]

     # File lib/macros.rb, line 169
169:     def validates_presence_of(*args)
170:       add_validations(args, ValidatesPresenceOf)
171:     end

Validates that the logic evaluates to true

  class Person
    include Validatable
    validates_true_for :first_name, :logic => lambda { first_name == 'Jamie' }
  end

The logic option is required.

Configuration options:

    * after_validate - A block that executes following the run of a validation
    * message - The message to add to the errors collection when the validation fails
    * times - The number of times the validation applies
    * level - The level at which the validation should occur
    * if - A block that when executed must return true of the validation will not occur
    * group - The group that this validation belongs to.  A validation can belong to multiple groups
    * logic - A block that executes to perform the validation

[Source]

     # File lib/macros.rb, line 193
193:     def validates_true_for(*args)
194:       add_validations(args, ValidatesTrueFor)
195:     end