validates!

This method is used to define validations that cannot be corrected by end users and are considered exceptional. So each validator defined with bang or :strict option set to true will always raise ActiveModel::StrictValidationFailed instead of adding error when validation fails. See validates for more information about the validation itself.

class Person include ActiveModel::Validations attr_accessor :name validates! :name, presence: true end person = Person.new person.name = '' person.valid? # => ActiveModel::StrictValidationFailed: Name can't be blank