Module: ActiveRecord::Validations::ClassMethods

Defined in:
lib/active_record/validations.rb

Overview

All of the following validations are defined in the class scope of the model that you’re interested in validating. They offer a more declarative way of specifying when the model is valid and when it is not. It is recommended to use these over the low-level calls to validate and validate_on_create when possible.

Instance Method Summary collapse

Instance Method Details

#validates_acceptance_of(*attr_names) ⇒ Object

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

class Person < ActiveRecord::Base
  validates_acceptance_of :terms_of_service
  validates_acceptance_of :eula, :message => "must be abided"
end

The terms_of_service attribute is entirely virtual. No database column is needed. This check is performed only if terms_of_service is not nil and by default on save.

Configuration options:

  • message - A custom error message (default is: “can’t be empty”)

  • on - Specifies when this validation is active (default is :save, other options :create, :update)

NOTE: The agreement is considered valid if it’s set to the string “1”. This makes it easy to relate it to an HTML checkbox.



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# File 'lib/active_record/validations.rb', line 108

def validates_acceptance_of(*attr_names)
  configuration = { :message => ActiveRecord::Errors.default_error_messages[:accepted], :on => :save }
  configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)

  for attr_name in attr_names
    attr_accessor(attr_name)
    class_eval(%(#{validation_method(configuration[:on])} %{errors.add('#{attr_name}', '#{configuration[:message]}') unless #{attr_name}.nil? or #{attr_name} == "1"}))
  end
end

#validates_associated(*attr_names) ⇒ Object

Validates whether the associated object or objects are all themselves valid. Works with any kind of assocation.

class Book < ActiveRecord::Base
  has_many :pages
  belongs_to :library

  validates_associated :pages, :library
end

Warning: If, after the above definition, you then wrote:

class Page < ActiveRecord::Base
  belongs_to :book

  validates_associated :book
end

this would specify a circular dependency and cause infinite recursion. The Rails team recommends against this practice.

Configuration options:

  • on Specifies when this validation is active (default is :save, other options :create, :update)



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# File 'lib/active_record/validations.rb', line 296

def validates_associated(*attr_names)
  configuration = { :message => ActiveRecord::Errors.default_error_messages[:invalid], :on => :save }
  configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)
  
  for attr_name in attr_names
    class_eval(%(#{validation_method(configuration[:on])} %{
      errors.add("#{attr_name}", "#{configuration[:message]}") unless
        (#{attr_name}.is_a?(Array) ? #{attr_name} : [#{attr_name}]).inject(true){ |memo, record| memo and (record.nil? or record.valid?) }
    }))
  end
end

#validates_confirmation_of(*attr_names) ⇒ Object

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

Model:
  class Person < ActiveRecord::Base
    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" %>

The person has to already have a password attribute (a column in the people table), but the password_confirmation is virtual. It exists only as an in-memory variable for validating the password. This check is performed only if password_confirmation is not nil and by default on save.

Configuration options:

  • message - A custom error message (default is: “doesn’t match confirmation”)

  • on - Specifies when this validation is active (default is :save, other options :create, :update)



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# File 'lib/active_record/validations.rb', line 83

def validates_confirmation_of(*attr_names)
  configuration = { :message => ActiveRecord::Errors.default_error_messages[:confirmation], :on => :save }
  configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)

  for attr_name in attr_names
    attr_accessor "#{attr_name}_confirmation"
    class_eval(%(#{validation_method(configuration[:on])} %{errors.add('#{attr_name}', "#{configuration[:message]}") unless #{attr_name}_confirmation.nil? or #{attr_name} == #{attr_name}_confirmation}))
  end
end

#validates_format_of(*attr_names) ⇒ Object

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

class Person < ActiveRecord::Base
  validates_format_of :email, :with => /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/, :on => :create
end

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

Configuration options:

  • message - A custom error message (default is: “is invalid”)

  • with - The regular expression used to validate the format with (note: must be supplied!)

  • on Specifies when this validation is active (default is :save, other options :create, :update)

Raises:

  • (ArgumentError) 


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# File 'lib/active_record/validations.rb', line 236

def validates_format_of(*attr_names)
  configuration = { :message => ActiveRecord::Errors.default_error_messages[:invalid], :on => :save, :with => nil }
  configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)

  raise(ArgumentError, "A regular expression must be supplied as the :with option of the configuration hash") unless configuration[:with].is_a?(Regexp)

  for attr_name in attr_names 
    class_eval(%(#{validation_method(configuration[:on])} %{errors.add("#{attr_name}", "#{configuration[:message]}") unless #{attr_name} and #{attr_name}.to_s.match(/#{Regexp.quote(configuration[:with].source)}/)}))
  end
end

#validates_inclusion_of(*attr_names) ⇒ Object

Validates whether the value of the specified attribute is available in a particular enumerable object.

class Person < ActiveRecord::Base
  validates_inclusion_of :gender, :in=>%w( m f ), :message=>"woah! what are you then!??!!"
  validates_inclusion_of :age, :in=>0..99
end

Configuration options:

  • in - An enumerable object of available items

  • message - Specifieds a customer error message (default is: “is not included in the list”)

  • allows_nil - If set to true, skips this validation if the attribute is null (default is: false)

Raises:

  • (ArgumentError) 


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# File 'lib/active_record/validations.rb', line 258

def validates_inclusion_of(*attr_names)
  configuration = { :message => ActiveRecord::Errors.default_error_messages[:inclusion], :on => :save }
  configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)
  enum = configuration[:in] || configuration[:within]
  allow_nil = configuration[:allow_nil]

  raise(ArgumentError, "An object with the method include? is required must be supplied as the :in option of the configuration hash") unless enum.respond_to?("include?")

  for attr_name in attr_names
    if allow_nil
      class_eval(%(#{validation_method(configuration[:on])} %{errors.add("#{attr_name}", "#{configuration[:message]}") unless #{attr_name}.nil? or (#{enum.inspect}).include?(#{attr_name}) }))
    else
      class_eval(%(#{validation_method(configuration[:on])} %{errors.add("#{attr_name}", "#{configuration[:message]}") unless (#{enum.inspect}).include?(#{attr_name}) }))
    end
  end
end

#validates_length_of(*attr_names) ⇒ Object

Validates that the specified attribute matches the length restrictions supplied. Only one option can be used at a time:

class Person < ActiveRecord::Base
  validates_length_of :first_name, :maximum=>30
  validates_length_of :last_name, :maximum=>30, :message=>"less than %d if you don't mind"
  validates_length_of :user_name, :within => 6..20, :too_long => "pick a shorter name", :too_short => "pick a longer name"
  validates_length_of :fav_bra_size, :minimum=>1, :too_short=>"please enter at least %d character"
  validates_length_of :smurf_leader, :is=>4, :message=>"papa is spelled with %d characters... don't play me."
end

Configuration options:

  • minimum - The minimum size of the attribute

  • maximum - The maximum size of the attribute

  • is - The exact size of the attribute

  • within - A range specifying the minimum and maximum size of the attribute

  • in - A synonym(or alias) for :within

  • too_long - The error message if the attribute goes over the maximum (default is: “is too long (max is %d characters)”)

  • too_short - The error message if the attribute goes under the minimum (default is: “is too short (min is %d characters)”)

  • wrong_length - The error message if using the :is method and the attribute is the wrong size (default is: “is the wrong length (should be %d characters)”)

  • message - The error message to use for a :minimum, :maximum, or :is violation. An alias of the appropriate too_long/too_short/wrong_length message

  • on - Specifies when this validation is active (default is :save, other options :create, :update)

Raises:

  • (ArgumentError) 


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# File 'lib/active_record/validations.rb', line 154

def validates_length_of(*attr_names)
  configuration = { :too_long => ActiveRecord::Errors.default_error_messages[:too_long], :too_short => ActiveRecord::Errors.default_error_messages[:too_short], :wrong_length => ActiveRecord::Errors.default_error_messages[:wrong_length], :on => :save }
  configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)

  # you must use one of 4 options, :within, :maximum, :minimum, or :is
  within = configuration[:within] || configuration[:in]
  maximum = configuration[:maximum]
  minimum = configuration[:minimum]
  is = configuration[:is]
  
  raise(ArgumentError, "The :within, :maximum, :minimum, or :is options must be passed in the configuration hash") unless within or maximum or minimum or is
  # but not more than 1 of them at a time
  options_used = 0
  options_used += 1 if within
  options_used += 1 if maximum
  options_used += 1 if minimum
  options_used += 1 if is
  raise(ArgumentError, "The :within, :maximum, :minimum, and :is options are mutually exclusive") if options_used > 1

  option_to_use = within || maximum || minimum || is
  for attr_name in attr_names
    if within
      raise(ArgumentError, "The :within option must be a Range") unless within.kind_of?(Range)
      class_eval(%(#{validation_method(configuration[:on])} %{errors.add_on_boundary_breaking('#{attr_name}', #{within}, "#{configuration[:too_long]}", "#{configuration[:too_short]}")}))
    elsif maximum
      raise(ArgumentError, "The :maximum option must be a Fixnum") unless maximum.kind_of?(Fixnum)
      msg = configuration[:message] || configuration[:too_long]
      msg = (msg % maximum) rescue msg
      class_eval(%(#{validation_method(configuration[:on])} %{errors.add( '#{attr_name}', '#{msg}') if #{attr_name}.to_s.length > #{maximum}  }))
    elsif minimum
      raise(ArgumentError, "The :minimum option must be a Fixnum") unless minimum.kind_of?(Fixnum)
      msg = configuration[:message] || configuration[:too_short]
      msg = (msg % minimum) rescue msg
      class_eval(%(#{validation_method(configuration[:on])} %{errors.add( '#{attr_name}', '#{msg}') if #{attr_name}.to_s.length < #{minimum}  }))
    else
      raise(ArgumentError, "The :is option must be a Fixnum") unless is.kind_of?(Fixnum)
      msg = configuration[:message] || configuration[:wrong_length]
      msg = (msg % is) rescue msg
      class_eval(%(#{validation_method(configuration[:on])} %{errors.add( '#{attr_name}', '#{msg}') if #{attr_name}.to_s.length != #{is}  }))
    end
  end        
end

#validates_presence_of(*attr_names) ⇒ Object

Validates that the specified attributes are neither nil nor empty. Happens by default on save.

Configuration options:

  • message - A custom error message (default is: “has already been taken”)

  • on - Specifies when this validation is active (default is :save, other options :create, :update)



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# File 'lib/active_record/validations.rb', line 123

def validates_presence_of(*attr_names)
  configuration = { :message => ActiveRecord::Errors.default_error_messages[:empty], :on => :save }
  configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)

  for attr_name in attr_names
    class_eval(%(#{validation_method(configuration[:on])} %{errors.add_on_empty('#{attr_name}', "#{configuration[:message]}")}))
  end
end

#validates_uniqueness_of(*attr_names) ⇒ Object

Validates whether the value of the specified attributes are unique across the system. Useful for making sure that only one user can be named “davidhh”.

class Person < ActiveRecord::Base
  validates_uniqueness_of :user_name, :scope => "account_id"
end

When the record is created, a check is performed to make sure that no record exist in the database with the given value for the specified attribute (that maps to a column). When the record is updated, the same check is made but disregarding the record itself.

Configuration options:

  • message - Specifies a custom error message (default is: “has already been taken”)

  • scope - Ensures that the uniqueness is restricted to a condition of “scope = record.scope”



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# File 'lib/active_record/validations.rb', line 210

def validates_uniqueness_of(*attr_names)
  configuration = { :message => ActiveRecord::Errors.default_error_messages[:taken] }
  configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)

  for attr_name in attr_names
    if scope = configuration[:scope]
      class_eval(%(validate %{errors.add('#{attr_name}', '#{configuration[:message]}') if self.class.find_first(new_record? ? ['#{attr_name} = ? AND #{scope} = ?', #{attr_name}, #{scope}] : ["#{attr_name} = ? AND \\\#{self.class.primary_key} <> ? AND #{scope} = ?", #{attr_name}, id, #{scope}])}))
    else
      class_eval(%(validate %{errors.add('#{attr_name}', '#{configuration[:message]}') if self.class.find_first(new_record? ? ['#{attr_name} = ?', #{attr_name}] : ["#{attr_name} = ? AND \\\#{self.class.primary_key} <> ?", #{attr_name}, id])}))
    end
  end
end