Bedingtes Aktualisieren eines DynamoDB-Elements mit einer TTL mithilfe eines SDK AWS

Die folgenden Codebeispiele zeigen, wie die TTL eines Elements bedingt aktualisiert wird.

Java

SDK für Java 2.x

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
package com.amazon.samplelib.ttl;

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;
import software.amazon.awssdk.utils.ImmutableMap;

import java.util.Map;
import java.util.Optional;

public class UpdateTTLConditional {
    public static void main(String[] args) {
        final String usage = """
                Usage:
                    <tableName> <primaryKey> <sortKey> <newTtlAttribute> <region>
                Where:
                    tableName - The Amazon DynamoDB table being queried.
                    primaryKey - The name of the primary key. Also known as the hash or partition key.
                    sortKey - The name of the sort key. Also known as the range attribute.
                    newTtlAttribute - New attribute name (as part of the update command)
                    region (optional) - The AWS region that the Amazon DynamoDB table is located in. (Default: us-east-1)
                """;
        // Optional "region" parameter - if args list length is NOT 3 or 4, short-circuit exit.
        if (!(args.length == 4 || args.length == 5)) {
            System.out.println(usage);
            System.exit(1);
        }
        final String tableName = args[0];
        final String primaryKey = args[1];
        final String sortKey = args[2];
        final String newTtlAttribute = args[3];
        Region region = Optional.ofNullable(args[4]).isEmpty() ? Region.US_EAST_1 : Region.of(args[4]);

        // Get current time in epoch second format
        final long currentTime = System.currentTimeMillis() / 1000;
        // Calculate expiration time 90 days from now in epoch second format
        final long expireDate = currentTime + (90 * 24 * 60 * 60);
        // An expression that defines one or more attributes to be updated, the action to be performed on them, and new values for them.
        final String updateExpression = "SET newTtlAttribute = :val1";
        // A condition that must be satisfied in order for a conditional update to succeed.
        final String conditionExpression = "expireAt > :val2";

        final ImmutableMap<String, AttributeValue> keyMap =
                ImmutableMap.of("primaryKey", AttributeValue.fromS(primaryKey),
                        "sortKey", AttributeValue.fromS(sortKey));
        final Map<String, AttributeValue> expressionAttributeValues = ImmutableMap.of(
                ":val1", AttributeValue.builder().s(newTtlAttribute).build(),
                ":val2", AttributeValue.builder().s(String.valueOf(expireDate)).build()
        );

        final UpdateItemRequest request = UpdateItemRequest.builder()
                .tableName(tableName)
                .key(keyMap)
                .updateExpression(updateExpression)
                .conditionExpression(conditionExpression)
                .expressionAttributeValues(expressionAttributeValues)
                .build();
        try (DynamoDbClient ddb = DynamoDbClient.builder()
                .region(region)
                .build()) {
            final UpdateItemResponse response = ddb.updateItem(request);
            System.out.println(tableName + " UpdateItem operation with conditional TTL successful. Request id is "
                    + response.responseMetadata().requestId());
        } catch (ResourceNotFoundException e) {
            System.err.format("Error: The Amazon DynamoDB table \"%s\" can't be found.\n", tableName);
            System.exit(1);
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
        System.exit(0);
    }
}

• Einzelheiten zur API finden Sie UpdateItemin der AWS SDK for Java 2.x API-Referenz.

JavaScript

SDK für JavaScript (v3)

Aktualisieren Sie TTL für ein vorhandenes DynamoDB-Element in einer Tabelle mit einer Bedingung.

import { DynamoDBClient, UpdateItemCommand } from "@aws-sdk/client-dynamodb";
import { marshall, unmarshall } from "@aws-sdk/util-dynamodb";

const updateDynamoDBItem = async (tableName, region, partitionKey, sortKey, newAttribute) => {
    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    const currentTime = Math.floor(Date.now() / 1000);

    const params = {
        TableName: tableName,
        Key: marshall({
            artist: partitionKey,
            album: sortKey
        }),
        UpdateExpression: "SET newAttribute = :newAttribute",
        ConditionExpression: "expireAt > :expiration",
        ExpressionAttributeValues: marshall({
            ':newAttribute': newAttribute,
            ':expiration': currentTime
        }),
        ReturnValues: "ALL_NEW"
    };

    try {
        const response = await client.send(new UpdateItemCommand(params));
        const responseData = unmarshall(response.Attributes);
        console.log("Item updated successfully: ", responseData);
        return responseData;
    } catch (error) {
        if (error.name === "ConditionalCheckFailedException") {
            console.log("Condition check failed: Item's 'expireAt' is expired.");
        } else {
            console.error("Error updating item: ", error);
        }
        throw error;
    }
};

// Enter your values here
updateDynamoDBItem('your-table-name', "us-east-1",'your-partition-key-value', 'your-sort-key-value', 'your-new-attribute-value');

• Einzelheiten zur API finden Sie unter UpdateItemAPI-Referenz.AWS SDK for JavaScript

Python

SDK für Python (Boto3)

# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0
import boto3
from datetime import datetime, timedelta
from botocore.exceptions import ClientError

def update_dynamodb_item(table_name, region, primary_key, sort_key, ttl_attribute):
    """
    Updates an existing record in a DynamoDB table with a new or updated TTL attribute.

    :param table_name: Name of the DynamoDB table
    :param region: AWS Region of the table - example `us-east-1`
    :param primary_key: one attribute known as the partition key.
    :param sort_key: Also known as a range attribute.
    :param ttl_attribute: name of the TTL attribute in the target DynamoDB table
    :return:
    """
    try:
        dynamodb = boto3.resource('dynamodb', region_name=region)
        table = dynamodb.Table(table_name)

        # Generate updated TTL in epoch second format
        updated_expiration_time = int((datetime.now() + timedelta(days=90)).timestamp())

        # Define the update expression for adding/updating a new attribute
        update_expression = "SET newAttribute = :val1"

        # Define the condition expression for checking if 'expireAt' is not expired
        condition_expression = "expireAt > :val2"

        # Define the expression attribute values
        expression_attribute_values = {
            ':val1': ttl_attribute,
            ':val2': updated_expiration_time
        }

        response = table.update_item(
            Key={
                'primaryKey': primary_key,
                'sortKey': sort_key
            },
            UpdateExpression=update_expression,
            ConditionExpression=condition_expression,
            ExpressionAttributeValues=expression_attribute_values
        )

        print("Item updated successfully.")
        return response['ResponseMetadata']['HTTPStatusCode']  # Ideally a 200 OK
    except ClientError as e:
        if e.response['Error']['Code'] == "ConditionalCheckFailedException":
            print("Condition check failed: Item's 'expireAt' is expired.")
        else:
            print(f"Error updating item: {e}")
    except Exception as e:
        print(f"Error updating item: {e}")

# replace with your values
update_dynamodb_item('your-table-name', 'us-east-1', 'your-partition-key-value', 'your-sort-key-value',
                     'your-ttl-attribute-value')

• Einzelheiten zur API finden Sie UpdateItemin AWS SDK for Python (Boto3) API Reference.

Eine vollständige Liste der AWS SDK-Entwicklerhandbücher und Codebeispiele finden Sie unter. DynamoDB mit einem SDK verwenden AWS Dieses Thema enthält auch Informationen zu den ersten Schritten und Details zu früheren SDK-Versionen.