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Class: ActiveModel::Errors

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Instance Chain:
self, ::Enumerable
Inherits: Object
Defined in: activemodel/lib/active_model/errors.rb

Overview

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 Translation you will not need to implement the last two. Likewise, using 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..

Constant Summary

Class Method Summary

Instance Attribute Summary

::Enumerable - Included

#many?

Returns true if the enumerable has more than 1 element.

Instance Method Summary

::Enumerable - Included

#exclude?

The negative of the Enumerable#include?.

#index_by

Convert an enumerable to a hash.

#pluck

Convert an enumerable to an array based on the given key.

#sum

Calculates a sum from the elements.

#without

Returns a copy of the enumerable without the specified elements.

Constructor Details

.new(base) ⇒ 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
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 74

def initialize(base)
  @base     = base
  @messages = apply_default_array({})
  @details = apply_default_array({})
end

Instance Attribute Details

#blank? (readonly)

Alias for #empty?.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 212

alias :blank? :empty?

#details (readonly)

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 65

attr_reader :messages, :details

#empty?Boolean (readonly) Also known as: #blank?

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
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 209

def empty?
  size.zero?
end

#messages (readonly)

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# File 'activemodel/lib/active_model/errors.rb', line 65

attr_reader :messages, :details

Instance Method Details

#[](attribute)

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"]
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 149

def [](attribute)
  messages[attribute.to_sym]
end

#add(attribute, message = :invalid, options = {})

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 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}]}
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 295

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 = {}) ⇒ Boolean

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 an option, then it returns true with the correct option, or false with an incorrect or missing option.

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
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 324

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)

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"]}
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 235

def as_json(options = nil)
  to_hash(options && options[:full_messages])
end

#clear

Clear the error messages.

person.errors.full_messages # => ["name cannot be nil"]
person.errors.clear
person.errors.full_messages # => []
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 115

def clear
  messages.clear
  details.clear
end

#count

Alias for #size.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 182

alias :count :size

#delete(key)

Delete messages for key. Returns the deleted messages.

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

  
# File 'activemodel/lib/active_model/errors.rb', line 138

def delete(key)
  attribute = key.to_sym
  details.delete(attribute)
  messages.delete(attribute)
end

#each

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
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 167

def each
  messages.each_key do |attribute|
    messages[attribute].each { |error| yield attribute, error }
  end
end

#full_message(attribute, message)

Returns a full message for a given attribute.

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

  
# File 'activemodel/lib/active_model/errors.rb', line 367

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 Also known as: #to_a

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"]
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 344

def full_messages
  map { |attribute, message| full_message(attribute, message) }
end

#full_messages_for(attribute)

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"]
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 359

def full_messages_for(attribute)
  attribute = attribute.to_sym
  messages[attribute].map { |message| full_message(attribute, message) }
end

#generate_message(attribute, type = :invalid, options = {})

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

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 401

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

  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}"
  else
    defaults = []
  end

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

  key = defaults.shift
  defaults = options.delete(:message) if options[:message]
  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,
    object: @base
  }.merge!(options)

  I18n.translate(key, options)
end

#has_key?(attribute)

Alias for #include?.

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# File 'activemodel/lib/active_model/errors.rb', line 130

alias :has_key? :include?

#include?(attribute) ⇒ Boolean Also known as: #has_key?, #key?

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
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 126

def include?(attribute)
  attribute = attribute.to_sym
  messages.key?(attribute) && messages[attribute].present?
end

#key?(attribute)

Alias for #include?.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 131

alias :key? :include?

#keys

Returns all message keys.

person.errors.messages # => {:name=>["cannot be nil", "must be specified"]}
person.errors.keys     # => [:name]
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 198

def keys
  messages.select do |key, value|
    !value.empty?
  end.keys
end

#merge!(other)

Merges the errors from other.

other - The Errors instance.

Examples

person.errors.merge!(other)
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# File 'activemodel/lib/active_model/errors.rb', line 105

def merge!(other)
  @messages.merge!(other.messages) { |_, ary1, ary2| ary1 + ary2 }
  @details.merge!(other.details) { |_, ary1, ary2| ary1 + ary2 }
end

#size Also known as: #count

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
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 179

def size
  values.flatten.size
end

#to_a

Alias for #full_messages.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 347

alias :to_a :full_messages

#to_hash(full_messages = false)

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"]}
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 244

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 = {})

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>
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# File 'activemodel/lib/active_model/errors.rb', line 225

def to_xml(options = {})
  to_a.to_xml({ root: "errors", skip_types: true }.merge!(options))
end

#values

Returns all message values.

person.errors.messages # => {:name=>["cannot be nil", "must be specified"]}
person.errors.values   # => [["cannot be nil", "must be specified"]]
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 188

def values
  messages.select do |key, value|
    !value.empty?
  end.values
end