com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBAutoGenerator Maven / Gradle / Ivy
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/*
* Copyright 2016-2024 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;
}
}
}