TypeError：元组索引必须是整数，而不是str / django

I'm having an error with this:

我有一个错误:

cursor = connection.cursor()

cursor.execute("SELECT username as username, sum(ACCTSESSIONTIME) as total_acctsessiontime FROM RADUSAGE GROUP BY username LIMIT 0, 10")

usage_summary = cursor.fetchall()

for row in usage_summary:
    row['total_acctsessiontime'] = 0 if row['total_acctsessiontime'] is None else humanize_seconds(row['total_acctsessiontime'])
    row['total_acctinputoctets'] = 0 if row['total_acctinputoctets'] is None else naturalsize(row['total_acctinputoctets'])
    row['total_acctoutputoctets'] = 0 if row['total_acctoutputoctets'] is None else naturalsize(row['total_acctoutputoctets'])

return jsonify(cursor)
curs