public function getSolrFieldName($field, $classNames = null) {
		if (!$classNames) {
			$classNames = Config::inst()->get('SolrSearch', 'default_searchable_types');
		}
		if (!is_array($classNames)) {
			$classNames = array($classNames);
		}

		foreach ($classNames as $className) {
			if (!class_exists($className)) {
				continue;
			}
			$dummy = singleton($className);
			$fields = $this->objectToFields($dummy);
			if ($field == 'ID') {
				$field = 'SS_ID';
			}
			if (isset($fields[$field])) {
				$configForType = $this->getSearchableFieldsFor($className);
				$hint = isset($configForType[$field]) ? $configForType[$field] : false;
				return $this->mapper->mapFieldNameFromType($field, $fields[$field]['Type'], $hint);
			}
		}
	}