Ci sono altri AWS SDK esempi disponibili nel repository AWS Doc SDK Examples
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Aggiornamento condizionale di un elemento DynamoDB utilizzando un TTL AWS SDK
I seguenti esempi di codice mostrano come aggiornare in modo condizionale un elemento. TTL
- Java
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- SDKper Java 2.x
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// 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); } }
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Per API i dettagli, vedere UpdateItemin AWS SDK for Java 2.x APIReference.
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- JavaScript
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- SDKper JavaScript (v3)
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Aggiorna TTL un elemento DynamoDB esistente in una tabella, con una condizione.
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');
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Per API i dettagli, consulta la sezione UpdateItemReference AWS SDK for JavaScript API.
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- Python
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- SDKper Python (Boto3)
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# 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')
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Per API i dettagli, vedere UpdateItemPython (Boto3) Reference.AWS SDK API
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Accelera le letture con DAX
Crea un elemento con un TTL