Active Record validation is reported to and from this object, which is used by Base#save to determine whether the object is in a valid state to be saved. See usage example in Validations.

Methods
Included Modules
Public Class methods
default_error_messages()
     # File activerecord/lib/active_record/validations.rb, line 135
135:       def default_error_messages
136:         ActiveSupport::Deprecation.warn("ActiveRecord::Errors.default_error_messages has been deprecated. Please use I18n.translate('activerecord.errors.messages').")
137:         I18n.translate 'activerecord.errors.messages'
138:       end
Public Instance methods
[](attribute)

Alias for on

add(attribute, message = nil, options = {})

Adds an error message (messsage) to the attribute, which will be returned on a call to on(attribute) for the same attribute and ensure that this error object returns false when asked if empty?. 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 messsage is supplied, :invalid is assumed. If message is a Symbol, it will be translated, using the appropriate scope (see translate_error).

     # File activerecord/lib/active_record/validations.rb, line 160
160:     def add(attribute, message = nil, options = {})
161:       options[:message] = options.delete(:default) if options[:default].is_a?(Symbol)
162:       error, message = message, nil if message.is_a?(Error)
163: 
164:       @errors[attribute.to_s] ||= []
165:       @errors[attribute.to_s] << (error || Error.new(@base, attribute, message, options))
166:     end
add_on_blank(attributes, custom_message = nil)

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

     # File activerecord/lib/active_record/validations.rb, line 178
178:     def add_on_blank(attributes, custom_message = nil)
179:       for attr in [attributes].flatten
180:         value = @base.respond_to?(attr.to_s) ? @base.send(attr.to_s) : @base[attr.to_s]
181:         add(attr, :blank, :default => custom_message) if value.blank?
182:       end
183:     end
add_on_empty(attributes, custom_message = nil)

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

     # File activerecord/lib/active_record/validations.rb, line 169
169:     def add_on_empty(attributes, custom_message = nil)
170:       for attr in [attributes].flatten
171:         value = @base.respond_to?(attr.to_s) ? @base.send(attr.to_s) : @base[attr.to_s]
172:         is_empty = value.respond_to?(:empty?) ? value.empty? : false
173:         add(attr, :empty, :default => custom_message) unless !value.nil? && !is_empty
174:       end
175:     end
add_to_base(msg)

Adds an error to the base object instead of any particular attribute. This is used to report errors that don‘t tie to any specific attribute, but rather to the object as a whole. These error messages don‘t get prepended with any field name when iterating with each_full, so they should be complete sentences.

     # File activerecord/lib/active_record/validations.rb, line 150
150:     def add_to_base(msg)
151:       add(:base, msg)
152:     end
clear()

Removes all errors that have been added.

     # File activerecord/lib/active_record/validations.rb, line 297
297:     def clear
298:       @errors = ActiveSupport::OrderedHash.new
299:     end
count()

Alias for size

each() {|attr, error.message| ...}

Yields each attribute and associated message per error added.

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

  company = Company.create(:address => '123 First St.')
  company.errors.each{|attr,msg| puts "#{attr} - #{msg}" }
  # => name - is too short (minimum is 5 characters)
  #    name - can't be blank
  #    address - can't be blank
     # File activerecord/lib/active_record/validations.rb, line 238
238:     def each
239:       @errors.each_key { |attr| @errors[attr].each { |error| yield attr, error.message } }
240:     end
each_error() {|attr, error| ...}

Yields each attribute and associated error per error added.

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

  company = Company.create(:address => '123 First St.')
  company.errors.each_error{|attr,err| puts "#{attr} - #{err.type}" }
  # => name - :too_short
  #    name - :blank
  #    address - :blank
     # File activerecord/lib/active_record/validations.rb, line 254
254:     def each_error
255:       @errors.each_key { |attr| @errors[attr].each { |error| yield attr, error } }
256:     end
each_full() {|msg| ...}

Yields each full error message added. So Person.errors.add("first_name", "can‘t be empty") will be returned through iteration as "First name can‘t be empty".

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

  company = Company.create(:address => '123 First St.')
  company.errors.each_full{|msg| puts msg }
  # => Name is too short (minimum is 5 characters)
  #    Name can't be blank
  #    Address can't be blank
     # File activerecord/lib/active_record/validations.rb, line 271
271:     def each_full
272:       full_messages.each { |msg| yield msg }
273:     end
empty?()

Returns true if no errors have been added.

     # File activerecord/lib/active_record/validations.rb, line 292
292:     def empty?
293:       @errors.empty?
294:     end
full_messages(options = {})

Returns all the full error messages in an array.

  class Company < ActiveRecord::Base
    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", "Address can't be blank"]
     # File activerecord/lib/active_record/validations.rb, line 285
285:     def full_messages(options = {})
286:       @errors.values.inject([]) do |full_messages, errors|
287:         full_messages + errors.map { |error| error.full_message }
288:       end
289:     end
generate_message(attribute, message = :invalid, options = {})
     # File activerecord/lib/active_record/validations.rb, line 335
335:     def generate_message(attribute, message = :invalid, options = {})
336:       Error.new(@base, attribute, message, options).to_s
337:     end
invalid?(attribute)

Returns true if the specified attribute has errors associated with it.

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

  company = Company.create(:address => '123 First St.')
  company.errors.invalid?(:name)      # => true
  company.errors.invalid?(:address)   # => false
     # File activerecord/lib/active_record/validations.rb, line 195
195:     def invalid?(attribute)
196:       !@errors[attribute.to_s].nil?
197:     end
length()

Alias for size

on(attribute)

Returns nil, if no errors are associated with the specified attribute. Returns the error message, if one error is associated with the specified attribute. Returns an array of error messages, if more than one error is associated with the specified attribute.

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

  company = Company.create(:address => '123 First St.')
  company.errors.on(:name)      # => ["is too short (minimum is 5 characters)", "can't be blank"]
  company.errors.on(:email)     # => "can't be blank"
  company.errors.on(:address)   # => nil
This method is also aliased as []
     # File activerecord/lib/active_record/validations.rb, line 212
212:     def on(attribute)
213:       attribute = attribute.to_s
214:       return nil unless @errors.has_key?(attribute)
215:       errors = @errors[attribute].map(&:to_s)
216:       errors.size == 1 ? errors.first : errors
217:     end
on_base()

Returns errors assigned to the base object through add_to_base according to the normal rules of on(attribute).

     # File activerecord/lib/active_record/validations.rb, line 222
222:     def on_base
223:       on(:base)
224:     end
size()

Returns the total number of errors added. Two errors added to the same attribute will be counted as such.

This method is also aliased as count length
     # File activerecord/lib/active_record/validations.rb, line 302
302:     def size
303:       @errors.values.inject(0) { |error_count, attribute| error_count + attribute.size }
304:     end
to_xml(options={})

Returns an XML representation of this error object.

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

  company = Company.create(:address => '123 First St.')
  company.errors.to_xml
  # =>  <?xml version="1.0" encoding="UTF-8"?>
  #     <errors>
  #       <error>Name is too short (minimum is 5 characters)</error>
  #       <error>Name can't be blank</error>
  #       <error>Address can't be blank</error>
  #     </errors>
     # File activerecord/lib/active_record/validations.rb, line 324
324:     def to_xml(options={})
325:       options[:root] ||= "errors"
326:       options[:indent] ||= 2
327:       options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])
328: 
329:       options[:builder].instruct! unless options.delete(:skip_instruct)
330:       options[:builder].errors do |e|
331:         full_messages.each { |msg| e.error(msg) }
332:       end
333:     end