public function convert(AccessInterface $object, $field, $value, $conversion)
	{
		$type = $this->getFieldType($object, $field);

		if (isset($this->filters[$type])) {
			if ($conversion == self::SETTER) {
				$value = $this->filters[$type]->convertToSetterValue($this, $object, $field, $value);
			} else if ($conversion == self::GETTER) {
				$value = $this->filters[$type]->convertToGetterValue($this, $object, $field, $value);
			}
		}

		if ($type == 'integer' && $value == '') {
			return NULL;
		}

		return $value;
	}