Method read_node_history

opcua/server/history_sql.py:101–134

(self, node_id, start, end, nb_values)

                                   'THEN MIN(SourceTimestamp) ELSE NULL END FROM "{tn}")', (count,))

    def read_node_history(self, node_id, start, end, nb_values):
        with self._lock:
            _c_read = self._conn.cursor()

            table = self._get_table_name(node_id)
            start_time, end_time, order, limit = self._get_bounds(start, end, nb_values)

            cont = None
            results = []

            # select values from the database; recreate UA Variant from binary
            try:
                for row in _c_read.execute('SELECT * FROM "{tn}" WHERE "SourceTimestamp" BETWEEN ? AND ? '
                                           'ORDER BY "_Id" {dir} LIMIT ?'.format(tn=table, dir=order),
                                           (start_time, end_time, limit,)):

                    # rebuild the data value object
                    dv = ua.DataValue(variant_from_binary(Buffer(row[6])))
                    dv.ServerTimestamp = row[1]
                    dv.SourceTimestamp = row[2]
                    dv.StatusCode = ua.StatusCode(row[3])

                    results.append(dv)

            except sqlite3.Error as e:
                self.logger.error('Historizing SQL Read Error for %s: %s', node_id, e)

            if nb_values:
                if len(results) > nb_values:
                    cont = results[nb_values].SourceTimestamp

                results = results[:nb_values]

            return results, cont

    def new_historized_event(self, source_id, evtypes, period, count=0):
        with self._lock: