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Module: ActiveModel::Validations

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Class Chain:
Defined in: activemodel/lib/active_model/validations.rb,
activemodel/lib/active_model/validations/absence.rb,
activemodel/lib/active_model/validations/acceptance.rb,
activemodel/lib/active_model/validations/callbacks.rb,
activemodel/lib/active_model/validations/clusivity.rb,
activemodel/lib/active_model/validations/comparability.rb,
activemodel/lib/active_model/validations/comparison.rb,
activemodel/lib/active_model/validations/confirmation.rb,
activemodel/lib/active_model/validations/exclusion.rb,
activemodel/lib/active_model/validations/format.rb,
activemodel/lib/active_model/validations/helper_methods.rb,
activemodel/lib/active_model/validations/inclusion.rb,
activemodel/lib/active_model/validations/length.rb,
activemodel/lib/active_model/validations/numericality.rb,
activemodel/lib/active_model/validations/presence.rb,
activemodel/lib/active_model/validations/resolve_value.rb,
activemodel/lib/active_model/validations/validates.rb,
activemodel/lib/active_model/validations/with.rb

Overview

Provides a full validation framework to your objects.

A minimal implementation could be:

class Person
  include ActiveModel::Validations

  attr_accessor :first_name, :last_name

  validates_each :first_name, :last_name do |record, attr, value|
    record.errors.add attr, "starts with z." if value.start_with?("z")
  end
end

Which provides you with the full standard validation stack that you know from Active Record:

person = Person.new
person.valid?                   # => true
person.invalid?                 # => false

person.first_name = 'zoolander'
person.valid?                   # => false
person.invalid?                 # => true
person.errors.messages          # => {first_name:["starts with z."]}

Note that Validations automatically adds an #errors method to your instances initialized with a new Errors object, so there is no need for you to do this manually.

Class Method Summary

::ActiveSupport::Concern - Extended

class_methods

Define class methods from given block.

included

Evaluate given block in context of base class, so that you can write class macros here.

prepended

Evaluate given block in context of base class, so that you can write class macros here.

append_features, prepend_features

Instance Attribute Summary

Instance Method Summary

DSL Calls

included

[ GitHub ]


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# File 'activemodel/lib/active_model/validations.rb', line 40

included do
  extend ActiveModel::Naming
  extend ActiveModel::Callbacks
  extend ActiveModel::Translation

  extend  HelperMethods
  include HelperMethods

  define_callbacks :validate, scope: :name

  class_attribute :_validators, instance_writer: false, default: Hash.new { |h, k| h[k] = [] }
end

Instance Attribute Details

#validation_context (rw)

Returns the context when running validations.

This is useful when running validations except a certain context (opposite to the on option).

class Person
  include ActiveModel::Validations

  attr_accessor :name
  validates :name, presence: true, if: -> { validation_context != :custom }
end

person = Person.new
person.valid?          #=> false
person.valid?(:new)    #=> false
person.valid?(:custom) #=> true
[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 454

def validation_context
  context_for_validation.context
end

#validation_context=(context) (rw, private)

[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 459

def validation_context=(context)
  context_for_validation.context = context
end

Instance Method Details

#context_for_validation (private)

[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 463

def context_for_validation
  @context_for_validation ||= ValidationContext.new
end

#errors

Returns the Errors object that holds all information about attribute error messages.

class Person
  include ActiveModel::Validations

  attr_accessor :name
  validates_presence_of :name
end

person = Person.new
person.valid? # => false
person.errors # => #<ActiveModel::Errors:0x007fe603816640 @messages={name:["can't be blank"]}>
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# File 'activemodel/lib/active_model/validations.rb', line 328

def errors
  @errors ||= Errors.new(self)
end

#freeze

[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 372

def freeze
  errors
  context_for_validation

  super
end

#init_internals (private)

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# File 'activemodel/lib/active_model/validations.rb', line 467

def init_internals
  super
  @errors = nil
  @context_for_validation = nil
end

#initialize_dup(other)

This method is for internal use only.

Clean the Errors object if instance is duped.

[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 310

def initialize_dup(other) # :nodoc:
  @errors = nil
  super
end

#invalid?(context = nil) ⇒ Boolean

Performs the opposite of #valid?. Returns true if errors were added, false otherwise.

class Person
  include ActiveModel::Validations

  attr_accessor :name
  validates_presence_of :name
end

person = Person.new
person.name = ''
person.invalid? # => true
person.name = 'david'
person.invalid? # => false

Context can optionally be supplied to define which callbacks to test against (the context is defined on the validations using :on).

class Person
  include ActiveModel::Validations

  attr_accessor :name
  validates_presence_of :name, on: :new
end

person = Person.new
person.invalid?       # => false
person.invalid?(:new) # => true
[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 408

def invalid?(context = nil)
  !valid?(context)
end

#raise_validation_error (private)

Raises:

[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 478

def raise_validation_error # :doc:
  raise(ValidationError.new(self))
end

#read_attribute_for_validation

Hook method defining how an attribute value should be retrieved. By default this is assumed to be an instance named after the attribute. Override this method in subclasses should you need to retrieve the value for a given attribute differently:

class MyClass
  include ActiveModel::Validations

  def initialize(data = {})
    @data = data
  end

  def read_attribute_for_validation(key)
    @data[key]
  end
end
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# File 'activemodel/lib/active_model/validations.rb', line 437

alias :read_attribute_for_validation :send

#run_validations! (private)

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# File 'activemodel/lib/active_model/validations.rb', line 473

def run_validations!
  _run_validate_callbacks
  errors.empty?
end

#valid?(context = nil) ⇒ Boolean Also known as: #validate

Runs all the specified validations and returns true if no errors were added otherwise false.

class Person
  include ActiveModel::Validations

  attr_accessor :name
  validates_presence_of :name
end

person = Person.new
person.name = ''
person.valid? # => false
person.name = 'david'
person.valid? # => true

Context can optionally be supplied to define which callbacks to test against (the context is defined on the validations using :on).

class Person
  include ActiveModel::Validations

  attr_accessor :name
  validates_presence_of :name, on: :new
end

person = Person.new
person.valid?       # => true
person.valid?(:new) # => false
[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 361

def valid?(context = nil)
  current_context = validation_context
  context_for_validation.context = context
  errors.clear
  run_validations!
ensure
  context_for_validation.context = current_context
end

#validate(context = nil)

Alias for #valid?.

[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 370

alias_method :validate, :valid?

#validate!(context = nil)

Runs all the validations within the specified context. Returns true if no errors are found, raises ValidationError otherwise.

Validations with no :on option will run no matter the context. Validations with some :on option will only run in the specified context.

[ GitHub ]

  
# File 'activemodel/lib/active_model/validations.rb', line 417

def validate!(context = nil)
  valid?(context) || raise_validation_error
end

#validates_with(*args, &block)

Passes the record off to the class or classes specified and allows them to add errors based on more complex conditions.

class Person
  include ActiveModel::Validations

  validate :instance_validations

  def instance_validations
    validates_with MyValidator
  end
end

Please consult the class method documentation for more information on creating your own validator.

You may also pass it multiple classes, like so:

class Person
  include ActiveModel::Validations

  validate :instance_validations, on: :create

  def instance_validations
    validates_with MyValidator, MyOtherValidator
  end
end

Standard configuration options (:on, :if and :unless), which are available on the class version of validates_with, should instead be placed on the validates method as these are applied and tested in the callback.

If you pass any additional configuration options, they will be passed to the class and available as options, please refer to the class version of this method for more information.

[ GitHub ]

  
# File 'activemodel/lib/active_model/validations/with.rb', line 144

def validates_with(*args, &block)
  options = args.extract_options!
  options[:class] = self.class

  args.each do |klass|
    validator = klass.new(options.dup, &block)
    validator.validate(self)
  end
end