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Class: ActiveModel::Errors

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

Overview

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 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..

Class Method Summary

Instance Attribute Summary

::Enumerable - Included

#many?

Returns true if the enumerable has more than 1 element.

Instance Method Summary

::Enumerable - Included

#compact_blank

Returns a new ::Array without the blank items.

#exclude?

The negative of the Enumerable#include?.

#excluding

Returns a copy of the enumerable excluding the specified elements.

#in_order_of

Returns a new ::Array where the order has been set to that provided in the series, based on the key of the objects in the original enumerable.

#including

Returns a new array that includes the passed elements.

#index_by

Convert an enumerable to a hash, using the block result as the key and the element as the value.

#index_with

Convert an enumerable to a hash, using the element as the key and the block result as the value.

#maximum

Calculates the maximum from the extracted elements.

#minimum

Calculates the minimum from the extracted elements.

#pick

Extract the given key from the first element in the enumerable.

#pluck

Extract the given key from each element in the enumerable.

#sole

Returns the sole item in the enumerable.

#without

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 117

def initialize(base)
  @base = base
  @errors = []
end

Instance Attribute Details

#errors (readonly) Also known as: #objects

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

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 107

attr_reader :errors

#objects (readonly)

Alias for #errors.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 108

alias :objects :errors

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 229

def [](attribute)
  messages_for(attribute)
end

#add(attribute, type = :invalid, **options)

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 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 342

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 = {}) ⇒ Boolean

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
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 372

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)

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 247

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

#attribute_names

Returns all error attribute names

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

  
# File 'activemodel/lib/active_model/errors.rb', line 237

def attribute_names
  @errors.map(&:attribute).uniq.freeze
end

#clear

Clears all errors. Clearing the errors does not, however, make the model valid. The next time the validations are run (for example, via ActiveRecord::Validations#valid?), the errors collection will be filled again if any validations fail.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 80

rdoc_method :method: clear

#delete(attribute, type = nil, **options)

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 215

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

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

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 276

def details
  hash = group_by_attribute.transform_values do |errors|
    errors.map(&:details)
  end
  hash.default = EMPTY_ARRAY
  hash.freeze
  hash
end

#each(&block)

Iterates through each error object.

person.errors.add(:name, :too_short, count: 2)
person.errors.each do |error|
  # Will yield <#ActiveModel::Error attribute=name, type=too_short,
                                    options={:count=>3}>
end
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 67

rdoc_method :method: each

#empty?Boolean

Returns true if there are no errors.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 90

rdoc_method :method: empty?

#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 451

def full_message(attribute, message)
  Error.full_message(attribute, message, @base)
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 415

def full_messages
  @errors.map(&:full_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 430

def full_messages_for(attribute)
  where(attribute).map(&:full_message).freeze
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 479

def generate_message(attribute, type = :invalid, options = {})
  Error.generate_message(attribute, type, @base, options)
end

#group_by_attribute

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

person.errors.group_by_attribute
# => {:name=>[<#ActiveModel::Error>, <#ActiveModel::Error>]}
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 289

def group_by_attribute
  @errors.group_by(&:attribute)
end

#has_key?(attribute)

Alias for #include?.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 207

alias :has_key? :include?

#import(error, override_options = {})

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.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 154

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) ⇒ 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 202

def include?(attribute)
  @errors.any? { |error|
    error.match?(attribute.to_sym)
  }
end

#key?(attribute)

Alias for #include?.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 208

alias :key? :include?

#merge!(other)

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

Parameters

  • other - The Errors instance.

Examples

person.errors.merge!(other)
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 174

def merge!(other)
  return errors if equal?(other)

  other.errors.each { |error|
    import(error)
  }
end

#messages

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

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 268

def messages
  hash = to_hash
  hash.default = EMPTY_ARRAY
  hash.freeze
  hash
end

#messages_for(attribute)

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"]
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 444

def messages_for(attribute)
  where(attribute).map(&:message)
end

#of_kind?(attribute, type = :invalid) ⇒ Boolean

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
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 395

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

#size

Returns number of errors.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 104

rdoc_method :method: size

#to_a

Alias for #full_messages.

[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 418

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 256

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)

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
[ GitHub ]

  
# File 'activemodel/lib/active_model/errors.rb', line 189

def where(attribute, type = nil, **options)
  attribute, type, options = normalize_arguments(attribute, type, **options)
  @errors.select { |error|
    error.match?(attribute, type, **options)
  }
end