📊 서버리스 투표/설문 앱

# voting-cast-vote Lambda (Python 3.12)
import json, boto3
 
ddb = boto3.resource('dynamodb')
table = ddb.Table('voting-app-votes')
 
def lambda_handler(event, context):
    try:
        body = json.loads(event.get('body', '{}'))
        option_id = body.get('optionId')
 
        if not option_id:
            return response(400, {'error': 'optionId가 필요합니다'})
 
        # Atomic Counter — 동시 요청에서도 정확한 카운트 보장
        result = table.update_item(
            Key={'optionId': option_id},
            UpdateExpression='ADD voteCount :inc',
            ExpressionAttributeValues={':inc': 1},
            ReturnValues='UPDATED_NEW'
        )
        new_count = int(result['Attributes']['voteCount'])
        return response(200, {
            'message': f'{option_id}에 투표 완료!',
            'optionId': option_id,
            'newCount': new_count
        })
    except Exception as e:
        return response(500, {'error': str(e)})
 
def response(status_code, body):
    return {
        'statusCode': status_code,
        'headers': {
            'Content-Type': 'application/json',
            'Access-Control-Allow-Origin': '*',
            'Access-Control-Allow-Methods': 'POST, OPTIONS',
        },
        'body': json.dumps(body, ensure_ascii=False)
    }

# voting-get-results Lambda (Python 3.12)
import json, boto3
from decimal import Decimal
 
ddb = boto3.resource('dynamodb')
table = ddb.Table('voting-app-votes')
 
class DecimalEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, Decimal):
            return int(obj)
        return super().default(obj)
 
def lambda_handler(event, context):
    try:
        result = table.scan()
        items = sorted(result['Items'], key=lambda x: x.get('voteCount', 0), reverse=True)
        total = sum(item.get('voteCount', 0) for item in items)
 
        return {
            'statusCode': 200,
            'headers': {
                'Content-Type': 'application/json',
                'Access-Control-Allow-Origin': '*',
                'Access-Control-Allow-Methods': 'GET, OPTIONS',
            },
            'body': json.dumps({
                'results': items,
                'totalVotes': total
            }, cls=DecimalEncoder, ensure_ascii=False)
        }
    except Exception as e:
        return {
            'statusCode': 500,
            'headers': {'Content-Type': 'application/json', 'Access-Control-Allow-Origin': '*'},
            'body': json.dumps({'error': str(e)})
        }