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Module: ActiveModel::Validations

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.to_s[0] == ?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

append_features, class_methods, included

Instance Method Summary

DSL Calls

included

[ GitHub ] 


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# File 'activemodel/lib/active_model/validations.rb', line 41

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

  extend  HelperMethods
  include HelperMethods

  attr_accessor :validation_context
  private :validation_context=
  define_callbacks :validate, scope: :name

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

Instance Method Details

#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"]}>
[ GitHub ] 

  


# File 'activemodel/lib/active_model/validations.rb', line 300



def errors
  @errors ||= Errors.new(self)
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 374



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


  



  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/validations.rb', line 394



alias :read_attribute_for_validation :send


  








  

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



  

    

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



Aliased as validate.



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 335



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


  








  

    #validate(context = nil)  
  



  

    

Alias for #valid?.


  



  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/validations.rb', line 343



alias_method :validate, :valid?


  








  

    #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 143



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

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