Class ActiveModel::Errors
In: lib/active_model/errors.rb
Parent: Object

Active Model Errors

Provides a modified OrderedHash that you can include in your object for handling error messages and interacting with Action Pack 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, "can not 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:

  p = Person.new
  p.validate!             # => ["can not be nil"]
  p.errors.full_messages  # => ["name can not be nil"]
  # etc..

Methods

[]   []=   add   add_on_blank   add_on_empty   added?   as_json   blank?   clear   count   delete   each   empty?   full_message   full_messages   generate_message   get   has_key?   include?   initialize_dup   keys   new   set   size   to_a   to_hash   to_xml   values  

Included Modules

Enumerable

Constants

CALLBACKS_OPTIONS = [:if, :unless, :on, :allow_nil, :allow_blank, :strict]

Attributes

messages  [R] 

Public Class methods

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

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

Public Instance methods

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"]

Adds to the supplied attribute the supplied error message.

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

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.

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.

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

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

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

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

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

blank?()

Alias for empty?

Clear the messages

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

Delete messages for key

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

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

Returns a full message for a given attribute.

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

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"]

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

Get messages for key

has_key?(error)

Alias for include?

Do the error messages include an error with key error?

Returns all message keys

Set messages for key to value

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

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"]

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>

Returns all message values

[Validate]