Ci sono altri AWS SDK esempi disponibili nel repository AWS Doc SDK Examples
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Interroga una tabella TTL DynamoDB per gli elementi utilizzando un AWS SDK
I seguenti esempi di codice mostrano come eseguire una query per TTL gli elementi.
- Java
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- SDKper Java 2.x
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Interroga l'espressione filtrata per raccogliere TTL elementi in una tabella 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);
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Per API i dettagli, consulta Query in Reference.AWS SDK for Java 2.x API
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- JavaScript
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- SDKper JavaScript (v3)
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// 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');
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Per API i dettagli, vedere Query in AWS SDK for JavaScript APIReference.
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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 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')
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Per API i dettagli, vedere Query in AWS SDKfor Python (Boto3) Reference. API
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Esecuzione di una query mediante PartiQL
Aggiorna un elemento TTL