class ActiveModel::Errors

Active Model Errors

Provides a modified Hash that you can include in your object for handling error messages and interacting with Action View helpers.

A minimal implementation could be:

class Person
  # Required dependency for ActiveModel::Errors
  extend ActiveModel::Naming

  def initialize
    @errors = ActiveModel::Errors.new(self)
  end

  attr_accessor :name
  attr_reader   :errors

  def validate!
    errors.add(:name, :blank, message: "cannot be nil") if name.nil?
  end

  # The following methods are needed to be minimally implemented

  def read_attribute_for_validation(attr)
    send(attr)
  end

  def self.human_attribute_name(attr, options = {})
    attr
  end

  def self.lookup_ancestors
    [self]
  end
end

The last three methods are required in your object for Errors to be able to generate error messages correctly and also handle multiple languages. Of course, if you extend your object with ActiveModel::Translation you will not need to implement the last two. Likewise, using ActiveModel::Validations will handle the validation related methods for you.

The above allows you to do:

person = Person.new
person.validate!            # => ["cannot be nil"]
person.errors.full_messages # => ["name cannot be nil"]
# etc..

Constants

CALLBACKS_OPTIONS
MESSAGE_OPTIONS

Attributes

details[R]
messages[R]

Public Class Methods

new(base) click to toggle source

Pass in the instance of the object that is using the errors object.

class Person
  def initialize
    @errors = ActiveModel::Errors.new(self)
  end
end
# File lib/active_model/errors.rb, line 78
def initialize(base)
  @base     = base
  @messages = apply_default_array({})
  @details = apply_default_array({})
end

Public Instance Methods

[](attribute) click to toggle source

When passed a symbol or a name of a method, returns an array of errors for the method.

person.errors[:name]  # => ["cannot be nil"]
person.errors['name'] # => ["cannot be nil"]
# File lib/active_model/errors.rb, line 164
def [](attribute)
  messages[attribute.to_sym]
end
add(attribute, message = :invalid, options = {}) click to toggle source

Adds message to the error messages and used validator type to details on attribute. More than one error can be added to the same attribute. If no message is supplied, :invalid is assumed.

person.errors.add(:name)
# => ["is invalid"]
person.errors.add(:name, :not_implemented, message: "must be implemented")
# => ["is invalid", "must be implemented"]

person.errors.messages
# => {:name=>["is invalid", "must be implemented"]}

person.errors.details
# => {:name=>[{error: :not_implemented}, {error: :invalid}]}

If message is a symbol, it will be translated using the appropriate scope (see generate_message).

If message is a proc, it will be called, allowing for things like Time.now to be used within an error.

If the :strict option is set to true, it will raise ActiveModel::StrictValidationFailed instead of adding the error. :strict option can also be set to any other exception.

person.errors.add(:name, :invalid, strict: true)
# => ActiveModel::StrictValidationFailed: Name is invalid
person.errors.add(:name, :invalid, strict: NameIsInvalid)
# => NameIsInvalid: Name is invalid

person.errors.messages # => {}

attribute should be set to :base if the error is not directly associated with a single attribute.

person.errors.add(:base, :name_or_email_blank,
  message: "either name or email must be present")
person.errors.messages
# => {:base=>["either name or email must be present"]}
person.errors.details
# => {:base=>[{error: :name_or_email_blank}]}
# File lib/active_model/errors.rb, line 310
def add(attribute, message = :invalid, options = {})
  message = message.call if message.respond_to?(:call)
  detail  = normalize_detail(message, options)
  message = normalize_message(attribute, message, options)
  if exception = options[:strict]
    exception = ActiveModel::StrictValidationFailed if exception == true
    raise exception, full_message(attribute, message)
  end

  details[attribute.to_sym]  << detail
  messages[attribute.to_sym] << message
end
added?(attribute, message = :invalid, options = {}) click to toggle source

Returns true if an error on the attribute with the given message is present, or false otherwise. message is treated the same as for add.

person.errors.add :name, :blank
person.errors.added? :name, :blank           # => true
person.errors.added? :name, "can't be blank" # => true

If the error message requires options, then it returns true with the correct options, or false with incorrect or missing options.

person.errors.add :name, :too_long, { count: 25 }
person.errors.added? :name, :too_long, count: 25                     # => true
person.errors.added? :name, "is too long (maximum is 25 characters)" # => true
person.errors.added? :name, :too_long, count: 24                     # => false
person.errors.added? :name, :too_long                                # => false
person.errors.added? :name, "is too long"                            # => false
# File lib/active_model/errors.rb, line 339
def added?(attribute, message = :invalid, options = {})
  message = message.call if message.respond_to?(:call)

  if message.is_a? Symbol
    details[attribute.to_sym].include? normalize_detail(message, options)
  else
    self[attribute].include? message
  end
end
as_json(options = nil) click to toggle source

Returns a Hash that can be used as the JSON representation for this object. You can pass the :full_messages option. This determines if the json object should contain full messages or not (false by default).

person.errors.as_json                      # => {:name=>["cannot be nil"]}
person.errors.as_json(full_messages: true) # => {:name=>["name cannot be nil"]}
# File lib/active_model/errors.rb, line 250
def as_json(options = nil)
  to_hash(options && options[:full_messages])
end
blank?()
Alias for: empty?
clear() click to toggle source

Clear the error messages.

person.errors.full_messages # => ["name cannot be nil"]
person.errors.clear
person.errors.full_messages # => []
# File lib/active_model/errors.rb, line 130
def clear
  messages.clear
  details.clear
end
count()
Alias for: size
delete(key) click to toggle source

Delete messages for key. Returns the deleted messages.

person.errors[:name]        # => ["cannot be nil"]
person.errors.delete(:name) # => ["cannot be nil"]
person.errors[:name]        # => []
# File lib/active_model/errors.rb, line 153
def delete(key)
  attribute = key.to_sym
  details.delete(attribute)
  messages.delete(attribute)
end
each() { |attribute, error| ... } click to toggle source

Iterates through each error key, value pair in the error messages hash. Yields the attribute and the error for that attribute. If the attribute has more than one error message, yields once for each error message.

person.errors.add(:name, :blank, message: "can't be blank")
person.errors.each do |attribute, error|
  # Will yield :name and "can't be blank"
end

person.errors.add(:name, :not_specified, message: "must be specified")
person.errors.each do |attribute, error|
  # Will yield :name and "can't be blank"
  # then yield :name and "must be specified"
end
# File lib/active_model/errors.rb, line 182
def each
  messages.each_key do |attribute|
    messages[attribute].each { |error| yield attribute, error }
  end
end
empty?() click to toggle source

Returns true if no errors are found, false otherwise. If the error message is a string it can be empty.

person.errors.full_messages # => ["name cannot be nil"]
person.errors.empty?        # => false
# File lib/active_model/errors.rb, line 224
def empty?
  size.zero?
end
Also aliased as: blank?
full_message(attribute, message) click to toggle source

Returns a full message for a given attribute.

person.errors.full_message(:name, 'is invalid') # => "Name is invalid"

The `“%{attribute} %{message}”` error format can be overridden with either

  • activemodel.errors.models.person/contacts/addresses.attributes.street.format

  • activemodel.errors.models.person/contacts/addresses.format

  • activemodel.errors.models.person.attributes.name.format

  • activemodel.errors.models.person.format

  • errors.format

# File lib/active_model/errors.rb, line 411
def full_message(attribute, message)
  return message if attribute == :base
  attribute = attribute.to_s

  if self.class.i18n_customize_full_message && @base.class.respond_to?(:i18n_scope)
    attribute = attribute.remove(/\[\d\]/)
    parts = attribute.split(".")
    attribute_name = parts.pop
    namespace = parts.join("/") unless parts.empty?
    attributes_scope = "#{@base.class.i18n_scope}.errors.models"

    if namespace
      defaults = @base.class.lookup_ancestors.map do |klass|
        [
          :"#{attributes_scope}.#{klass.model_name.i18n_key}/#{namespace}.attributes.#{attribute_name}.format",
          :"#{attributes_scope}.#{klass.model_name.i18n_key}/#{namespace}.format",
        ]
      end
    else
      defaults = @base.class.lookup_ancestors.map do |klass|
        [
          :"#{attributes_scope}.#{klass.model_name.i18n_key}.attributes.#{attribute_name}.format",
          :"#{attributes_scope}.#{klass.model_name.i18n_key}.format",
        ]
      end
    end

    defaults.flatten!
  else
    defaults = []
  end

  defaults << :"errors.format"
  defaults << "%{attribute} %{message}"

  attr_name = attribute.tr(".", "_").humanize
  attr_name = @base.class.human_attribute_name(attribute, default: attr_name)

  I18n.t(defaults.shift,
    default:  defaults,
    attribute: attr_name,
    message:   message)
end
full_messages() click to toggle source

Returns all the full error messages in an array.

class Person
  validates_presence_of :name, :address, :email
  validates_length_of :name, in: 5..30
end

person = Person.create(address: '123 First St.')
person.errors.full_messages
# => ["Name is too short (minimum is 5 characters)", "Name can't be blank", "Email can't be blank"]
# File lib/active_model/errors.rb, line 380
def full_messages
  map { |attribute, message| full_message(attribute, message) }
end
Also aliased as: to_a
full_messages_for(attribute) click to toggle source

Returns all the full error messages for a given attribute in an array.

class Person
  validates_presence_of :name, :email
  validates_length_of :name, in: 5..30
end

person = Person.create()
person.errors.full_messages_for(:name)
# => ["Name is too short (minimum is 5 characters)", "Name can't be blank"]
# File lib/active_model/errors.rb, line 395
def full_messages_for(attribute)
  attribute = attribute.to_sym
  messages[attribute].map { |message| full_message(attribute, message) }
end
generate_message(attribute, type = :invalid, options = {}) click to toggle source

Translates an error message in its default scope (activemodel.errors.messages).

Error messages are first looked up in activemodel.errors.models.MODEL.attributes.ATTRIBUTE.MESSAGE, if it's not there, it's looked up in activemodel.errors.models.MODEL.MESSAGE and if that is not there also, it returns the translation of the default message (e.g. activemodel.errors.messages.MESSAGE). The translated model name, translated attribute name and the value are available for interpolation.

When using inheritance in your models, it will check all the inherited models too, but only if the model itself hasn't been found. Say you have class Admin < User; end and you wanted the translation for the :blank error message for the title attribute, it looks for these translations:

  • activemodel.errors.models.admin.attributes.title.blank

  • activemodel.errors.models.admin.blank

  • activemodel.errors.models.user.attributes.title.blank

  • activemodel.errors.models.user.blank

  • any default you provided through the options hash (in the activemodel.errors scope)

  • activemodel.errors.messages.blank

  • errors.attributes.title.blank

  • errors.messages.blank

# File lib/active_model/errors.rb, line 479
def generate_message(attribute, type = :invalid, options = {})
  type = options.delete(:message) if options[:message].is_a?(Symbol)
  value = (attribute != :base ? @base.send(:read_attribute_for_validation, attribute) : nil)

  options = {
    model: @base.model_name.human,
    attribute: @base.class.human_attribute_name(attribute),
    value: value,
    object: @base
  }.merge!(options)

  if @base.class.respond_to?(:i18n_scope)
    i18n_scope = @base.class.i18n_scope.to_s
    defaults = @base.class.lookup_ancestors.flat_map do |klass|
      [ :"#{i18n_scope}.errors.models.#{klass.model_name.i18n_key}.attributes.#{attribute}.#{type}",
        :"#{i18n_scope}.errors.models.#{klass.model_name.i18n_key}.#{type}" ]
    end
    defaults << :"#{i18n_scope}.errors.messages.#{type}"

    catch(:exception) do
      translation = I18n.translate(defaults.first, **options.merge(default: defaults.drop(1), throw: true))
      return translation unless translation.nil?
    end unless options[:message]
  else
    defaults = []
  end

  defaults << :"errors.attributes.#{attribute}.#{type}"
  defaults << :"errors.messages.#{type}"

  key = defaults.shift
  defaults = options.delete(:message) if options[:message]
  options[:default] = defaults

  I18n.translate(key, **options)
end
has_key?(attribute)
Alias for: include?
include?(attribute) click to toggle source

Returns true if the error messages include an error for the given key attribute, false otherwise.

person.errors.messages        # => {:name=>["cannot be nil"]}
person.errors.include?(:name) # => true
person.errors.include?(:age)  # => false
# File lib/active_model/errors.rb, line 141
def include?(attribute)
  attribute = attribute.to_sym
  messages.key?(attribute) && messages[attribute].present?
end
Also aliased as: has_key?, key?
key?(attribute)
Alias for: include?
keys() click to toggle source

Returns all message keys.

person.errors.messages # => {:name=>["cannot be nil", "must be specified"]}
person.errors.keys     # => [:name]
# File lib/active_model/errors.rb, line 213
def keys
  messages.select do |key, value|
    !value.empty?
  end.keys
end
merge!(other) click to toggle source

Merges the errors from other.

other - The ActiveModel::Errors instance.

Examples

person.errors.merge!(other)
# File lib/active_model/errors.rb, line 109
def merge!(other)
  @messages.merge!(other.messages) { |_, ary1, ary2| ary1 + ary2 }
  @details.merge!(other.details) { |_, ary1, ary2| ary1 + ary2 }
end
of_kind?(attribute, message = :invalid) click to toggle source

Returns true if an error on the attribute with the given message is present, or false otherwise. message is treated the same as for add.

person.errors.add :age
person.errors.add :name, :too_long, { count: 25 }
person.errors.of_kind? :age                                            # => true
person.errors.of_kind? :name                                           # => false
person.errors.of_kind? :name, :too_long                                # => true
person.errors.of_kind? :name, "is too long (maximum is 25 characters)" # => true
person.errors.of_kind? :name, :not_too_long                            # => false
person.errors.of_kind? :name, "is too long"                            # => false
# File lib/active_model/errors.rb, line 360
def of_kind?(attribute, message = :invalid)
  message = message.call if message.respond_to?(:call)

  if message.is_a? Symbol
    details[attribute.to_sym].map { |e| e[:error] }.include? message
  else
    self[attribute].include? message
  end
end
size() click to toggle source

Returns the number of error messages.

person.errors.add(:name, :blank, message: "can't be blank")
person.errors.size # => 1
person.errors.add(:name, :not_specified, message: "must be specified")
person.errors.size # => 2
# File lib/active_model/errors.rb, line 194
def size
  values.flatten.size
end
Also aliased as: count
slice!(*keys) click to toggle source

Removes all errors except the given keys. Returns a hash containing the removed errors.

person.errors.keys                  # => [:name, :age, :gender, :city]
person.errors.slice!(:age, :gender) # => { :name=>["cannot be nil"], :city=>["cannot be nil"] }
person.errors.keys                  # => [:age, :gender]
# File lib/active_model/errors.rb, line 119
def slice!(*keys)
  keys = keys.map(&:to_sym)
  @details.slice!(*keys)
  @messages.slice!(*keys)
end
to_a()
Alias for: full_messages
to_hash(full_messages = false) click to toggle source

Returns a Hash of attributes with their error messages. If full_messages is true, it will contain full messages (see full_message).

person.errors.to_hash       # => {:name=>["cannot be nil"]}
person.errors.to_hash(true) # => {:name=>["name cannot be nil"]}
# File lib/active_model/errors.rb, line 259
def to_hash(full_messages = false)
  if full_messages
    messages.each_with_object({}) do |(attribute, array), messages|
      messages[attribute] = array.map { |message| full_message(attribute, message) }
    end
  else
    without_default_proc(messages)
  end
end
to_xml(options = {}) click to toggle source

Returns an xml formatted representation of the Errors hash.

person.errors.add(:name, :blank, message: "can't be blank")
person.errors.add(:name, :not_specified, message: "must be specified")
person.errors.to_xml
# =>
#  <?xml version=\"1.0\" encoding=\"UTF-8\"?>
#  <errors>
#    <error>name can't be blank</error>
#    <error>name must be specified</error>
#  </errors>
# File lib/active_model/errors.rb, line 240
def to_xml(options = {})
  to_a.to_xml({ root: "errors", skip_types: true }.merge!(options))
end
values() click to toggle source

Returns all message values.

person.errors.messages # => {:name=>["cannot be nil", "must be specified"]}
person.errors.values   # => [["cannot be nil", "must be specified"]]
# File lib/active_model/errors.rb, line 203
def values
  messages.select do |key, value|
    !value.empty?
  end.values
end

Private Instance Methods

apply_default_array(hash) click to toggle source
# File lib/active_model/errors.rb, line 553
def apply_default_array(hash)
  hash.default_proc = proc { |h, key| h[key] = [] }
  hash
end
normalize_detail(message, options) click to toggle source
# File lib/active_model/errors.rb, line 543
def normalize_detail(message, options)
  { error: message }.merge(options.except(*CALLBACKS_OPTIONS + MESSAGE_OPTIONS))
end
normalize_message(attribute, message, options) click to toggle source
# File lib/active_model/errors.rb, line 534
def normalize_message(attribute, message, options)
  case message
  when Symbol
    generate_message(attribute, message, options.except(*CALLBACKS_OPTIONS))
  else
    message
  end
end
without_default_proc(hash) click to toggle source
# File lib/active_model/errors.rb, line 547
def without_default_proc(hash)
  hash.dup.tap do |new_h|
    new_h.default_proc = nil
  end
end