ActiveModel::Errors

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 76
def initialize(base)
  @base     = base
  @messages = ActiveSupport::OrderedHash.new
end

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

p.errors[:name]   # => ["can not be nil"]
p.errors['name']  # => ["can not be nil"]

# File lib/active_model/errors.rb, line 124
def [](attribute)
  get(attribute.to_sym) || set(attribute.to_sym, [])
end

Adds to the supplied attribute the supplied error message.

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

# File lib/active_model/errors.rb, line 132
def []=(attribute, error)
  self[attribute] << error
end

Adds message to the error messages on attribute, which will be returned on a call to on(attribute) for the same attribute. More than one error can be added to the same attribute in which case an array will be returned on a call to on(attribute). If no message is supplied, :invalid is assumed.

If message is a symbol, it will be translated using the appropriate scope (see translate_error). If message is a proc, it will be called, allowing for things like Time.now to be used within an error.

# File lib/active_model/errors.rb, line 230
def add(attribute, message = nil, options = {})
  message ||= :invalid

  if message.is_a?(Symbol)
    message = generate_message(attribute, message, options.except(*CALLBACKS_OPTIONS))
  elsif message.is_a?(Proc)
    message = message.call
  end

  self[attribute] << message
end

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

# File lib/active_model/errors.rb, line 252
def add_on_blank(attributes, options = {})
  [attributes].flatten.each do |attribute|
    value = @base.send(:read_attribute_for_validation, attribute)
    add(attribute, :blank, options) if value.blank?
  end
end

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

# File lib/active_model/errors.rb, line 243
def add_on_empty(attributes, options = {})
  [attributes].flatten.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

Returns an ActiveSupport::OrderedHash that can be used as the JSON representation for this object.

# File lib/active_model/errors.rb, line 215
def as_json(options=nil)
  to_hash
end

Clear the messages

# File lib/active_model/errors.rb, line 95
def clear
  messages.clear
end

Returns the number of error messages.

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

# File lib/active_model/errors.rb, line 190
def count
  to_a.size
end

Delete messages for key

# File lib/active_model/errors.rb, line 115
def delete(key)
  messages.delete(key)
end

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.

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

p.errors.add(:name, "must be specified")
p.errors.each do |attribute, errors_array|
  # Will yield :name and "can't be blank"
  # then yield :name and "must be specified"
end

# File lib/active_model/errors.rb, line 150
def each
  messages.each_key do |attribute|
    self[attribute].each { |error| yield attribute, error }
  end
end

Returns true if no errors are found, false otherwise.

# File lib/active_model/errors.rb, line 195
def empty?
  all? { |k, v| v && v.empty? }
end

Returns all the full error messages in an array.

class Company
  validates_presence_of :name, :address, :email
  validates_length_of :name, :in => 5..30
end

company = Company.create(:address => '123 First St.')
company.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 269
def full_messages
  map { |attribute, message|
    if attribute == :base
      message
    else
      attr_name = attribute.to_s.gsub('.', '_').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
  }
end

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 310
def generate_message(attribute, type = :invalid, options = {})
  type = options.delete(:message) if options[:message].is_a?(Symbol)

  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

  defaults << options.delete(:message)
  defaults << :"#{@base.class.i18n_scope}.errors.messages.#{type}"
  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.class.model_name.human,
    :attribute => @base.class.human_attribute_name(attribute),
    :value => value
  }.merge(options)

  I18n.translate(key, options)
end

Get messages for key

# File lib/active_model/errors.rb, line 105
def get(key)
  messages[key]
end

Do the error messages include an error with key error?

# File lib/active_model/errors.rb, line 100
def include?(error)
  (v = messages[error]) && v.any?
end

Returns all message keys

# File lib/active_model/errors.rb, line 172
def keys
  messages.keys
end

Set messages for key to value

# File lib/active_model/errors.rb, line 110
def set(key, value)
  messages[key] = value
end

Returns the number of error messages.

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

# File lib/active_model/errors.rb, line 162
def size
  values.flatten.size
end

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

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

# File lib/active_model/errors.rb, line 181
def to_a
  full_messages
end

Returns an xml formatted representation of the Errors hash.

p.errors.add(:name, "can't be blank")
p.errors.add(:name, "must be specified")
p.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 210
def to_xml(options={})
  to_a.to_xml options.reverse_merge(:root => "errors", :skip_types => true)
end

Returns all message values

# File lib/active_model/errors.rb, line 167
def values
  messages.values
end