class ActiveModel::Errors

Active Model Errors

Provides error related functionalities 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..

Attributes

errors[R]

The actual array of Error objects This method is aliased to objects.

objects[R]

The actual array of Error objects This method is aliased to objects.

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 92
def initialize(base)
  @base = base
  @errors = []
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 204
def [](attribute)
  messages_for(attribute)
end
add(attribute, type = :invalid, **options) click to toggle source

Adds a new error of type on attribute. More than one error can be added to the same attribute. If no type is supplied, :invalid is assumed.

person.errors.add(:name)
# Adds <#ActiveModel::Error attribute=name, type=invalid>
person.errors.add(:name, :not_implemented, message: "must be implemented")
# Adds <#ActiveModel::Error attribute=name, type=not_implemented,
                            options={:message=>"must be implemented"}>

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

If type is a string, it will be used as error message.

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

person.errors.add(:name, :blank)
person.errors.messages
# => {:name=>["can't be blank"]}

person.errors.add(:name, :too_long, { count: 25 })
person.errors.messages
# => ["is too long (maximum is 25 characters)"]

If type 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 317
def add(attribute, type = :invalid, **options)
  attribute, type, options = normalize_arguments(attribute, type, **options)
  error = Error.new(@base, attribute, type, **options)

  if exception = options[:strict]
    exception = ActiveModel::StrictValidationFailed if exception == true
    raise exception, error.full_message
  end

  @errors.append(error)

  error
end
added?(attribute, type = :invalid, options = {}) click to toggle source

Returns true if an error matches provided attribute and type, or false otherwise. type 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 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 347
def added?(attribute, type = :invalid, options = {})
  attribute, type, options = normalize_arguments(attribute, type, **options)

  if type.is_a? Symbol
    @errors.any? { |error|
      error.strict_match?(attribute, type, **options)
    }
  else
    messages_for(attribute).include?(type)
  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 222
def as_json(options = nil)
  to_hash(options && options[:full_messages])
end
attribute_names() click to toggle source

Returns all error attribute names

person.errors.messages        # => {:name=>["cannot be nil", "must be specified"]}
person.errors.attribute_names # => [:name]
# File lib/active_model/errors.rb, line 212
def attribute_names
  @errors.map(&:attribute).uniq.freeze
end
delete(attribute, type = nil, **options) 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 190
def delete(attribute, type = nil, **options)
  attribute, type, options = normalize_arguments(attribute, type, **options)
  matches = where(attribute, type, **options)
  matches.each do |error|
    @errors.delete(error)
  end
  matches.map(&:message).presence
end
details() click to toggle source

Returns a Hash of attributes with an array of their error details.

# File lib/active_model/errors.rb, line 251
def details
  hash = group_by_attribute.transform_values do |errors|
    errors.map(&:details)
  end
  hash.default = EMPTY_ARRAY
  hash.freeze
  hash
end
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"
# File lib/active_model/errors.rb, line 426
def full_message(attribute, message)
  Error.full_message(attribute, message, @base)
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 390
def full_messages
  @errors.map(&:full_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 405
def full_messages_for(attribute)
  where(attribute).map(&:full_message).freeze
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 454
def generate_message(attribute, type = :invalid, options = {})
  Error.generate_message(attribute, type, @base, options)
end
group_by_attribute() click to toggle source

Returns a Hash of attributes with an array of their Error objects.

person.errors.group_by_attribute
# => {:name=>[<#ActiveModel::Error>, <#ActiveModel::Error>]}
# File lib/active_model/errors.rb, line 264
def group_by_attribute
  @errors.group_by(&:attribute)
end
has_key?(attribute)
Alias for: include?
import(error, override_options = {}) click to toggle source

Imports one error. Imported errors are wrapped as a NestedError, providing access to original error object. If attribute or type needs to be overridden, use override_options.

Options

  • :attribute - Override the attribute the error belongs to.

  • :type - Override type of the error.

# File lib/active_model/errors.rb, line 129
def import(error, override_options = {})
  [:attribute, :type].each do |key|
    if override_options.key?(key)
      override_options[key] = override_options[key].to_sym
    end
  end
  @errors.append(NestedError.new(@base, error, override_options))
end
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 177
def include?(attribute)
  @errors.any? { |error|
    error.match?(attribute.to_sym)
  }
end
Also aliased as: has_key?, key?
key?(attribute)
Alias for: include?
merge!(other) click to toggle source

Merges the errors from other, each Error wrapped as NestedError.

Parameters

Examples

person.errors.merge!(other)
# File lib/active_model/errors.rb, line 149
def merge!(other)
  return errors if equal?(other)

  other.errors.each { |error|
    import(error)
  }
end
messages() click to toggle source

Returns a Hash of attributes with an array of their error messages.

# File lib/active_model/errors.rb, line 243
def messages
  hash = to_hash
  hash.default = EMPTY_ARRAY
  hash.freeze
  hash
end
messages_for(attribute) click to toggle source

Returns all the 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.messages_for(:name)
# => ["is too short (minimum is 5 characters)", "can't be blank"]
# File lib/active_model/errors.rb, line 419
def messages_for(attribute)
  where(attribute).map(&:message)
end
of_kind?(attribute, type = :invalid) click to toggle source

Returns true if an error on the attribute with the given type is present, or false otherwise. type 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 370
def of_kind?(attribute, type = :invalid)
  attribute, type = normalize_arguments(attribute, type)

  if type.is_a? Symbol
    !where(attribute, type).empty?
  else
    messages_for(attribute).include?(type)
  end
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 231
def to_hash(full_messages = false)
  message_method = full_messages ? :full_message : :message
  group_by_attribute.transform_values do |errors|
    errors.map(&message_method)
  end
end
where(attribute, type = nil, **options) click to toggle source

Search for errors matching attribute, type, or options.

Only supplied params will be matched.

person.errors.where(:name) # => all name errors.
person.errors.where(:name, :too_short) # => all name errors being too short
person.errors.where(:name, :too_short, minimum: 2) # => all name errors being too short and minimum is 2
# File lib/active_model/errors.rb, line 164
def where(attribute, type = nil, **options)
  attribute, type, options = normalize_arguments(attribute, type, **options)
  @errors.select { |error|
    error.match?(attribute, type, **options)
  }
end

Private Instance Methods

normalize_arguments(attribute, type, **options) click to toggle source
# File lib/active_model/errors.rb, line 465
def normalize_arguments(attribute, type, **options)
  # Evaluate proc first
  if type.respond_to?(:call)
    type = type.call(@base, options)
  end

  [attribute.to_sym, type, options]
end