Consulta de elementos de TTL en una tabla de DynamoDB con un AWS SDK - Amazon DynamoDB

Consulta de elementos de TTL en una tabla de DynamoDB con un AWS SDK

En los siguientes ejemplos de código, se muestra cómo consultar elementos de TTL.

Java
SDK para Java 2.x

Consulte una expresión filtrada para recopilar elementos de TTL en una tabla de DynamoDB.

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.QueryRequest; import software.amazon.awssdk.services.dynamodb.model.QueryResponse; import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException; import software.amazon.awssdk.utils.ImmutableMap; import java.util.Map; import java.util.Optional; // Get current time in epoch second format (comparing against expiry attribute) final long currentTime = System.currentTimeMillis() / 1000; // A string that contains conditions that DynamoDB applies after the Query operation, but before the data is returned to you. final String keyConditionExpression = "#pk = :pk"; // The condition that specifies the key values for items to be retrieved by the Query action. final String filterExpression = "#ea > :ea"; final Map<String, String> expressionAttributeNames = ImmutableMap.of( "#pk", "primaryKey", "#ea", "expireAt"); final Map<String, AttributeValue> expressionAttributeValues = ImmutableMap.of( ":pk", AttributeValue.builder().s(primaryKey).build(), ":ea", AttributeValue.builder().s(String.valueOf(currentTime)).build() ); final QueryRequest request = QueryRequest.builder() .tableName(tableName) .keyConditionExpression(keyConditionExpression) .filterExpression(filterExpression) .expressionAttributeNames(expressionAttributeNames) .expressionAttributeValues(expressionAttributeValues) .build(); try (DynamoDbClient ddb = DynamoDbClient.builder() .region(region) .build()) { final QueryResponse response = ddb.query(request); System.out.println(tableName + " Query operation with TTL successful. Request id is " + response.responseMetadata().requestId()); // Print the items that are not expired for (Map<String, AttributeValue> item : response.items()) { System.out.println(item.toString()); } } 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);
  • Para obtener información sobre la API, consulte Query en la referencia de la API de AWS SDK for Java 2.x.

JavaScript
SDK para JavaScript (v3)
// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. // SPDX-License-Identifier: Apache-2.0 import { DynamoDBClient, QueryCommand } from "@aws-sdk/client-dynamodb"; import { marshall, unmarshall } from "@aws-sdk/util-dynamodb"; async function queryDynamoDBItems(tableName, region, primaryKey) { const client = new DynamoDBClient({ region: region, endpoint: `https://dynamodb.${region}.amazonaws.com` }); const currentTime = Math.floor(Date.now() / 1000); const params = { TableName: tableName, KeyConditionExpression: "#pk = :pk", FilterExpression: "#ea > :ea", ExpressionAttributeNames: { "#pk": "primaryKey", "#ea": "expireAt" }, ExpressionAttributeValues: marshall({ ":pk": primaryKey, ":ea": currentTime }) }; try { const { Items } = await client.send(new QueryCommand(params)); Items.forEach(item => { console.log(unmarshall(item)) }); return Items; } catch (err) { console.error(`Error querying items: ${err}`); throw err; } } //enter your own values here queryDynamoDBItems('your-table-name', 'your-partition-key-value');
  • Para obtener información sobre la API, consulte Query en la referencia de la API de AWS SDK for JavaScript.

Python
SDK para Python (Boto3)
# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. # SPDX-License-Identifier: Apache-2.0 import boto3 from datetime import datetime def query_dynamodb_items(table_name, partition_key): """ :param table_name: Name of the DynamoDB table :param partition_key: :return: """ try: # Initialize a DynamoDB resource dynamodb = boto3.resource('dynamodb', region_name='us-east-1') # Specify your table table = dynamodb.Table(table_name) # Get the current time in epoch format current_time = int(datetime.now().timestamp()) # Perform the query operation with a filter expression to exclude expired items # response = table.query( # KeyConditionExpression=boto3.dynamodb.conditions.Key('partitionKey').eq(partition_key), # FilterExpression=boto3.dynamodb.conditions.Attr('expireAt').gt(current_time) # ) response = table.query( KeyConditionExpression=dynamodb.conditions.Key('partitionKey').eq(partition_key), FilterExpression=dynamodb.conditions.Attr('expireAt').gt(current_time) ) # Print the items that are not expired for item in response['Items']: print(item) except Exception as e: print(f"Error querying items: {e}") # Call the function with your values query_dynamodb_items('Music', 'your-partition-key-value')
  • Para obtener información sobre la API, consulte Query en la referencia de la API de AWS SDK para Python (Boto3).

Para obtener una lista completa de las guías para desarrolladores del AWS SDK y ejemplos de código, consulte Uso de DynamoDB con un SDK de AWS. En este tema también se incluye información sobre cómo comenzar a utilizar el SDK y detalles sobre sus versiones anteriores.