Bulk index action.

        :param payload: Decoded message body.
        :returns: Dictionary defining an Elasticsearch bulk 'index' action.

def _index_action(self, payload):
        """Bulk index action.

        :param payload: Decoded message body.
        :returns: Dictionary defining an Elasticsearch bulk 'index' action.
        """
        record = Record.get_record(payload['id'])
        index, doc_type = self.record_to_index(record)

        return {
            '_op_type': 'index',
            '_index': index,
            '_type': doc_type,
            '_id': str(record.id),
            '_version': record.revision_id,
            '_version_type': self._version_type,
            '_source': self._prepare_record(record, index, doc_type),
        }