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The AWS Java SDK for Amazon DynamoDB module holds the client classes that are used for communicating with Amazon DynamoDB Service

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/*
 * Copyright 2016-2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *    http://aws.amazon.com/apache2.0
 *
 * This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
 * OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and
 * limitations under the License.
 */
package com.amazonaws.services.dynamodbv2.datamodeling;

import com.amazonaws.annotation.SdkInternalApi;

/**
 * Generator interface for auto-generating attribute values.
 *
 * 

Auto-generation may be controlled by {@link DynamoDBAutoGenerateStrategy}, *

{@link DynamoDBAutoGenerateStrategy#CREATE}, instructs to generate when * creating the item. The mapper, determines an item is new, or overwriting, * if it's current value is {@code null}. There is a limitiation when performing * partial updates using either, * {@link DynamoDBMapperConfig.SaveBehavior#UPDATE_SKIP_NULL_ATTRIBUTES}, or * {@link DynamoDBMapperConfig.SaveBehavior#APPEND_SET}. A new value will only * be generated if the mapper is also generating the key.

* *

{@link DynamoDBAutoGenerateStrategy#ALWAYS}, instructs to always generate * a new value, applied on any save or batch write operation. * *

May be used in combination with {@link DynamoDBAutoGenerated}.

* * @param The object's field/property value type. * * @see com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBAutoGenerated */ public interface DynamoDBAutoGenerator { /** * Gets the auto-generate strategy. */ public DynamoDBAutoGenerateStrategy getGenerateStrategy(); /** * Generates a new value given the current value (or null) if applicable. */ public T generate(T currentValue); /** * A generator which holds the {@link DynamoDBAutoGenerateStrategy}. */ @SdkInternalApi static abstract class AbstractGenerator implements DynamoDBAutoGenerator { private final DynamoDBAutoGenerateStrategy strategy; protected AbstractGenerator(DynamoDBAutoGenerateStrategy strategy) { this.strategy = strategy; } @Override public DynamoDBAutoGenerateStrategy getGenerateStrategy() { return this.strategy; } } }




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