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Diffstat (limited to 'guides/source/active_record_validations.md')
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diff --git a/guides/source/active_record_validations.md b/guides/source/active_record_validations.md index 32641d04c1..7dbe464f34 100644 --- a/guides/source/active_record_validations.md +++ b/guides/source/active_record_validations.md @@ -530,6 +530,47 @@ field you should use `validates :field_name, inclusion: { in: [true, false] }`. The default error message is _"can't be empty"_. +### `absence` + +This helper validates that the specified attributes are absent. It uses the +`present?` method to check if the value is not either nil or a blank string, that +is, a string that is either empty or consists of whitespace. + +```ruby +class Person < ActiveRecord::Base + validates :name, :login, :email, absence: true +end +``` + +If you want to be sure that an association is absent, you'll need to test +whether the associated object itself is absent, and not the foreign key used +to map the association. + +```ruby +class LineItem < ActiveRecord::Base + belongs_to :order + validates :order, absence: true +end +``` + +In order to validate associated records whose absence is required, you must +specify the `:inverse_of` option for the association: + +```ruby +class Order < ActiveRecord::Base + has_many :line_items, inverse_of: :order +end +``` + +If you validate the absence of an object associated via a `has_one` or +`has_many` relationship, it will check that the object is neither `present?` nor +`marked_for_destruction?`. + +Since `false.present?` is false, if you want to validate the presence of a boolean +field you should use `validates :field_name, inclusion: { in: [true, false] }`. + +The default error message is _"must be blank"_. + ### `uniqueness` This helper validates that the attribute's value is unique right before the |