com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBVersionAttribute Maven / Gradle / Ivy

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The Amazon Web Services SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).

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/*
 * Copyright 2011-2014 Amazon Technologies, Inc.
 *
 * 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 java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Annotation for marking a property as an optimistic locking version attribute.
 * Applied to the getter method or the class field for the class's version
 * property. If the annotation is applied directly to the class field, the
 * corresponding getter and setter must be declared in the same class.
 * 
 * Only nullable, integral numeric types (e.g. Integer, Long) can be used as
 * version properties. On a save() operation, the {@link DynamoDBMapper} will
 * attempt to increment the version property and assert that the service's value
 * matches the client's. New objects will be assigned a version of 1 when saved.
 * 
 * Note that for batchWrite, and by extension batchSave and batchDelete, no
 * version checks are performed, as required by the
 * {@link com.amazonaws.services.dynamodbv2.AmazonDynamoDB#batchWriteItem(BatchWriteItemRequest)}
 * API.
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD})
public @interface DynamoDBVersionAttribute {
    /**
     * Optional parameter when the name of the attribute as stored in DynamoDB
     * should differ from the name used by the getter / setter.
     */
    String attributeName() default "";
}