Python script for server side of IoT BOT to monitor BLE tags (for AWS lambda)

BLETagMonitor_lambda.py

# -*- coding: utf-8 -*-
from datetime import datetime, timedelta, timezone
import boto3
from boto3.session import Session
from boto3.dynamodb.conditions import Key

TIMEOUT_SEC = 180


def lambda_handler(event, context):

    # 現在時刻を取得
    JST = timezone(timedelta(hours=+9), 'JST')
    now = datetime.now(JST)
    now_ut = int(now.strftime('%s'))
    now_dt = now.strftime('%Y/%m/%d %H:%M:%S (JST)')

    try:
        # dynamodbのテーブルに接続
        region = "ap-northeast-1"
        session = Session(
            region_name = region
        )
        dynamodb = session.resource('dynamodb')
        table = dynamodb.Table('{your_table_name}')
        response = {}

        # 入力がタグ情報の場合、テーブルにタグ情報を追加（状態は不在=0）
        if 'tag_info' in event.keys():
            response['inserted'] = []
            for info in event['tag_info']:
                tid  = info['tid']
                name = info['name']
                table.put_item(
                    Item = {
                        'tid' : tid,
                        'name' : name,
                        'exists' : 0,
                        'utime' : now_ut,
                        'datetime' : now_dt
                    }
                )
                response['inserted'].append({'tid': tid, 'name': name})

        # 入力がタグ状態の場合、タグ状態に基づいてテーブルを更新しアクションを決定
        #   アクション：1=出現,0=消失
        if 'tag_detected' in event.keys():
            response['updated'] = []
            queryData = table.scan()
            for data in queryData['Items']:
                tid = data['tid']
                name = data['name']
                exists = data['exists']
                utime = data['utime']
                dtime = data['datetime']

                if tid in event['tag_detected']:
                    table.update_item(
                        Key = {
                            'tid' : tid
                        },
                        UpdateExpression = "set #e=:e, utime=:ut, #d=:dt",
                        ExpressionAttributeNames = { "#e":"exists", "#d":"datetime" },
                        ExpressionAttributeValues = {
                            ':e'  : 1,
                            ':ut' : now_ut,
                            ':dt' : now_dt
                        }
                    )
                    if not exists:
                        response['updated'].append({
                            'name': name,
                            'action': 1
                        })

                elif exists and now_ut > utime + TIMEOUT_SEC:
                    table.update_item(
                        Key = {
                            'tid' : tid
                        },
                        UpdateExpression = "set #e=:e",
                        ExpressionAttributeNames = { "#e": "exists" },
                        ExpressionAttributeValues = {
                            ':e'  : 0
                        }
                    )
                    response['updated'].append({
                        'name': name,
                        'action': 0
                    })

        # モニターからの受信ログを記録
        if 'monitor_name' in event.keys():
            table_log = dynamodb.Table('BLETagMonitor_MonitorLog')
            table_log.put_item(
                Item = {
                    'name' : event['monitor_name'],
                    'utime' : now_ut,
                    'datetime' : now_dt
                }
            )

        return response

    except Exception as e:
        print(e)