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::Translations 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
Included Modules
Constants
CALLBACKS_OPTIONS = [:if, :unless, :on, :allow_nil, :allow_blank]
Public Class methods
new(base)

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

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

[ show source ]

      # File activemodel/lib/active_model/errors.rb, line 75
75:     def initialize(base)
76:       @base = base
77:       super()
78:     end
Public Instance methods
[](attribute)

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"]
This method is also aliased as get

[ show source ]

      # File activemodel/lib/active_model/errors.rb, line 88
88:     def [](attribute)
89:       get(attribute.to_sym) || set(attribute.to_sym, [])
90:     end
[]=(attribute, error)

Adds to the supplied attribute the supplied error message. 

  p.errors[:name] = "must be set"
  p.errors[:name] # => ['must be set']
This method is also aliased as set

[ show source ]

      # File activemodel/lib/active_model/errors.rb, line 96
96:     def []=(attribute, error)
97:       self[attribute.to_sym] << error
98:     end
add(attribute, message = nil, options = {})

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.

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 180
180:     def add(attribute, message = nil, options = {})
181:       message ||= :invalid
182: 
183:       if message.is_a?(Symbol)
184:         message = generate_message(attribute, message, options.except(*CALLBACKS_OPTIONS))
185:       elsif message.is_a?(Proc)
186:         message = message.call
187:       end
188: 
189:       self[attribute] << message
190:     end
add_on_blank(attributes, options = {})

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

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 209
209:     def add_on_blank(attributes, options = {})
210:       if options && !options.is_a?(Hash)
211:         options = { :message => options }
212:         ActiveSupport::Deprecation.warn            "ActiveModel::Errors#add_on_blank(attributes, custom_message) has been deprecated.\n" +
213:           "Instead of passing a custom_message pass an options Hash { :message => custom_message }."
214:       end
215: 
216:       [attributes].flatten.each do |attribute|
217:         value = @base.send(:read_attribute_for_validation, attribute)
218:         add(attribute, :blank, options) if value.blank?
219:       end
220:     end
add_on_empty(attributes, options = {})

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

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 193
193:     def add_on_empty(attributes, options = {})
194:       if options && !options.is_a?(Hash)
195:         options = { :message => options }
196:         ActiveSupport::Deprecation.warn            "ActiveModel::Errors#add_on_empty(attributes, custom_message) has been deprecated.\n" +
197:           "Instead of passing a custom_message pass an options Hash { :message => custom_message }."
198:       end
199: 
200:       [attributes].flatten.each do |attribute|
201:         value = @base.send(:read_attribute_for_validation, attribute)
202:         is_empty = value.respond_to?(:empty?) ? value.empty? : false
203:         add(attribute, :empty, options) if value.nil? || is_empty
204:       end
205:     end
as_json(options=nil)

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

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 169
169:     def as_json(options=nil)
170:       self
171:     end
count()

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

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 144
144:     def count
145:       to_a.size
146:     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. 

  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

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 114
114:     def each
115:       each_key do |attribute|
116:         self[attribute].each { |error| yield attribute, error }
117:       end
118:     end
empty?()

Returns true if there are any errors, false if not.

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 149
149:     def empty?
150:       all? { |k, v| v && v.empty? }
151:     end
full_messages()

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", "Address can't be blank"]

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 233
233:     def full_messages
234:       full_messages = []
235: 
236:       each do |attribute, messages|
237:         messages = Array.wrap(messages)
238:         next if messages.empty?
239: 
240:         if attribute == :base
241:           messages.each {|m| full_messages << m }
242:         else
243:           attr_name = attribute.to_s.gsub('.', '_').humanize
244:           attr_name = @base.class.human_attribute_name(attribute, :default => attr_name)
245:           options = { :default => "%{attribute} %{message}", :attribute => attr_name }
246: 
247:           messages.each do |m|
248:             full_messages << I18n.t(:"errors.format", options.merge(:message => m))
249:           end
250:         end
251:       end
252: 
253:       full_messages
254:     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 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:

  1. activemodel.errors.models.admin.attributes.title.blank
  2. activemodel.errors.models.admin.blank
  3. activemodel.errors.models.user.attributes.title.blank
  4. activemodel.errors.models.user.blank
  5. any default you provided through the options hash (in the activemodel.errors scope)
  6. activemodel.errors.messages.blank
  7. errors.attributes.title.blank
  8. errors.messages.blank

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 281
281:     def generate_message(attribute, type = :invalid, options = {})
282:       type = options.delete(:message) if options[:message].is_a?(Symbol)
283: 
284:       if options[:default]
285:         ActiveSupport::Deprecation.warn            "Giving :default as validation option to errors.add has been deprecated.\n" +
286:           "Please use :message instead."
287:         options[:message] = options.delete(:default)
288:       end
289: 
290:       defaults = @base.class.lookup_ancestors.map do |klass|
291:         [ :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.underscore}.attributes.#{attribute}.#{type}",
292:           :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.underscore}.#{type}" ]
293:       end
294: 
295:       defaults << options.delete(:message)
296:       defaults << :"#{@base.class.i18n_scope}.errors.messages.#{type}"
297:       defaults << :"errors.attributes.#{attribute}.#{type}"
298:       defaults << :"errors.messages.#{type}"
299: 
300:       defaults.compact!
301:       defaults.flatten!
302: 
303:       key = defaults.shift
304:       value = (attribute != :base ? @base.send(:read_attribute_for_validation, attribute) : nil)
305: 
306:       options = {
307:         :default => defaults,
308:         :model => @base.class.model_name.human,
309:         :attribute => @base.class.human_attribute_name(attribute),
310:         :value => value
311:       }.merge(options)
312: 
313:       I18n.translate(key, options)
314:     end
size()

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

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 126
126:     def size
127:       values.flatten.size
128:     end
to_a()

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"]

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 135
135:     def to_a
136:       full_messages
137:     end
to_xml(options={})

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>

[ show source ]

       # File activemodel/lib/active_model/errors.rb, line 164
164:     def to_xml(options={})
165:       to_a.to_xml options.reverse_merge(:root => "errors", :skip_types => true)
166:     end