class ActiveModel::Errors - activemodel-4.2.3 Documentation

# 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, "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 Person.human_attribute_name(attr, options = {})
        attr
      end

      def Person.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

### Attributes

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 70
    def initialize(base)
      @base     = base
      @messages = {}
    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 135
    def [](attribute)
      get(attribute.to_sym) || set(attribute.to_sym, [])
    end

[]=(attribute, error) click to toggle source

Adds to the supplied attribute the supplied error message.

    person.errors[:name] = "must be set"
    person.errors[:name] # => ['must be set']

    # File lib/active_model/errors.rb, line 143
    def []=(attribute, error)
      self[attribute] << error
    end

add(attribute, message = :invalid, options = {}) click to toggle source

Adds `message` to the error messages 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, 'must be implemented')
    # => ["is invalid", "must be implemented"]

    person.errors.messages
    # => {:name=>["must be implemented", "is 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, nil, strict: true)
    # => ActiveModel::StrictValidationFailed: name is invalid
    person.errors.add(:name, nil, 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, "either name or email must be present")
    person.errors.messages
    # => {:base=>["either name or email must be present"]}

    # File lib/active_model/errors.rb, line 298
    def add(attribute, message = :invalid, options = {})
      message = normalize_message(attribute, message, options)
      if exception = options[:strict]
        exception = ActiveModel::StrictValidationFailed if exception == true
        raise exception, full_message(attribute, message)
      end

      self[attribute] << message
    end

add_on_blank(attributes, options = {}) click to toggle source

Will add an error message to each of the attributes in `attributes` that is blank (using Object#blank?).

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

    # File lib/active_model/errors.rb, line 328
    def add_on_blank(attributes, options = {})
      Array(attributes).each do |attribute|
        value = @base.send(:read_attribute_for_validation, attribute)
        add(attribute, :blank, options) if value.blank?
      end
    end

add_on_empty(attributes, options = {}) click to toggle source

Will add an error message to each of the attributes in `attributes` that is empty.

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

    # File lib/active_model/errors.rb, line 314
    def add_on_empty(attributes, options = {})
      Array(attributes).each do |attribute|
        value = @base.send(:read_attribute_for_validation, attribute)
        is_empty = value.respond_to?(:empty?) ? value.empty? : false
        add(attribute, :empty, options) if value.nil? || is_empty
      end
    end

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

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

    person.errors.add :name, :blank
    person.errors.added? :name, :blank # => true

    # File lib/active_model/errors.rb, line 340
    def added?(attribute, message = :invalid, options = {})
      message = normalize_message(attribute, message, options)
      self[attribute].include? message
    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 244
    def as_json(options=nil)
      to_hash(options && options[:full_messages])
    end

blank?()

aliases empty?

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 85
    def clear
      messages.clear
    end

count() click to toggle source

Returns the number of error messages.

    person.errors.add(:name, "can't be blank")
    person.errors.count # => 1
    person.errors.add(:name, "must be specified")
    person.errors.count # => 2

    # File lib/active_model/errors.rb, line 208
    def count
      to_a.size
    end

delete(key) click to toggle source

Delete messages for `key`. Returns the deleted messages.

    person.errors.get(:name)    # => ["cannot be nil"]
    person.errors.delete(:name) # => ["cannot be nil"]
    person.errors.get(:name)    # => nil

    # File lib/active_model/errors.rb, line 126
    def delete(key)
      messages.delete(key)
    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, "can't be blank")
    person.errors.each do |attribute, error|
      # Will yield :name and "can't be blank"
    end

    person.errors.add(:name, "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 161
    def each
      messages.each_key do |attribute|
        self[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 217
    def empty?
      all? { |k, v| v && v.empty? && !v.is_a?(String) }
    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"

    # File lib/active_model/errors.rb, line 376
    def full_message(attribute, message)
      return message if attribute == :base
      attr_name = attribute.to_s.tr('.', '_').humanize
      attr_name = @base.class.human_attribute_name(attribute, default: attr_name)
      I18n.t(:"errors.format", {
        default:  "%{attribute} %{message}",
        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 355
    def full_messages
      map { |attribute, message| full_message(attribute, message) }
    end

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 369
    def full_messages_for(attribute)
      (get(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 `models.MODEL.attributes.ATTRIBUTE.MESSAGE`, if it's not there, it's looked up in `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 411
    def generate_message(attribute, type = :invalid, options = {})
      type = options.delete(:message) if options[:message].is_a?(Symbol)

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

      defaults << options.delete(:message)
      defaults << :"#{@base.class.i18n_scope}.errors.messages.#{type}" if @base.class.respond_to?(:i18n_scope)
      defaults << :"errors.attributes.#{attribute}.#{type}"
      defaults << :"errors.messages.#{type}"

      defaults.compact!
      defaults.flatten!

      key = defaults.shift
      value = (attribute != :base ? @base.send(:read_attribute_for_validation, attribute) : nil)

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

      I18n.translate(key, options)
    end

get(key) click to toggle source

Get messages for `key`.

    person.errors.messages   # => {:name=>["cannot be nil"]}
    person.errors.get(:name) # => ["cannot be nil"]
    person.errors.get(:age)  # => nil

    # File lib/active_model/errors.rb, line 108
    def get(key)
      messages[key]
    end

has_key?(attribute)

aliases include?

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 95
    def include?(attribute)
      messages[attribute].present?
    end

Also aliased as: has_key?, key?
key?(attribute)

aliases include?

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 189
    def keys
      messages.keys
    end

set(key, value) click to toggle source

Set messages for `key` to `value`.

    person.errors.get(:name) # => ["cannot be nil"]
    person.errors.set(:name, ["can't be nil"])
    person.errors.get(:name) # => ["can't be nil"]

    # File lib/active_model/errors.rb, line 117
    def set(key, value)
      messages[key] = value
    end

size() click to toggle source

Returns the number of error messages.

    person.errors.add(:name, "can't be blank")
    person.errors.size # => 1
    person.errors.add(:name, "must be specified")
    person.errors.size # => 2

    # File lib/active_model/errors.rb, line 173
    def size
      values.flatten.size
    end

to_a() click to toggle source

Returns an array of error messages, with the attribute name included.

    person.errors.add(:name, "can't be blank")
    person.errors.add(:name, "must be specified")
    person.errors.to_a # => ["name can't be blank", "name must be specified"]

    # File lib/active_model/errors.rb, line 198
    def to_a
      full_messages
    end

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 253
    def to_hash(full_messages = false)
      if full_messages
        self.messages.each_with_object({}) do |(attribute, array), messages|
          messages[attribute] = array.map { |message| full_message(attribute, message) }
        end
      else
        self.messages.dup
      end
    end

to_xml(options={}) click to toggle source

Returns an xml formatted representation of the Errors hash.

    person.errors.add(:name, "can't be blank")
    person.errors.add(:name, "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 234
    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 181
    def values
      messages.values
    end

### Private Instance Methods

normalize_message(attribute, message, options) click to toggle source

    # File lib/active_model/errors.rb, line 445
    def normalize_message(attribute, message, options)
      case message
      when Symbol
        generate_message(attribute, message, options.except(*CALLBACKS_OPTIONS))
      when Proc
        message.call
      else
        message
      end
    end