Module: ActiveRecord::Validations::ClassMethods

Defined in:
lib/validates_existence.rb

Instance Method Summary collapse

Instance Method Details

#validates_existence_of(*attr_names) ⇒ Object

The validates_existence_of validator checks that a foreign key in a belongs_to association points to an exisiting record. If :allow_nil => true, then the key itself may be nil. A non-nil key requires that the foreign object must exist. Works with polymorphic belongs_to.



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# File 'lib/validates_existence.rb', line 14

def validates_existence_of(*attr_names)
  configuration = { :message => "does not exist", :on => :save }
  configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)

  send(validation_method(configuration[:on]), configuration) do |record|
    attr_names.each do |attr_name|
      attr_name = attr_name.to_s.sub(/_id$/, '').to_sym
      unless (assoc = reflect_on_association(attr_name)) && assoc.macro == :belongs_to
        raise ArgumentError, "Cannot validate existence of :#{attr_name} because it is not a belongs_to association."
      end
      fk_value = record.send assoc.primary_key_name.to_sym
      unless fk_value.nil? && configuration[:allow_nil] || fk_value.blank? && configuration[:allow_blank]
        if (foreign_type = assoc.options[:foreign_type]) # polymorphic
          foreign_type_value = record[assoc.options[:foreign_type]]
          if !foreign_type_value.blank?
            assoc_class = foreign_type_value.constantize
          else
            record.errors.add(attr_name, configuration[:message])
            next
          end
        else # not polymorphic
          assoc_class = assoc.klass
        end
        record.errors.add(attr_name, configuration[:message]) unless assoc_class && assoc_class.exists?(fk_value)
      end
    end
  end
end