software.amazon.awssdk.enhanced.dynamodb.extensions

Class VersionedRecordExtension

java.lang.Object

software.amazon.awssdk.enhanced.dynamodb.extensions.VersionedRecordExtension

All Implemented Interfaces:

DynamoDbEnhancedClientExtension

public final class VersionedRecordExtension
extends Object
implements DynamoDbEnhancedClientExtension

This extension implements optimistic locking on record writes by means of a 'record version number' that is used to automatically track each revision of the record as it is modified. To use this extension, first load it as part of your MappedTable instantiation:

 
 MappedTable.builder()
            .extendWith(VersionedRecordExtension.builder().build())
            .build();
 
 

Then create an attribute in your model that will be used to store the record version number. This attribute must be an 'integer' type numeric (long or integer), and you need to tag it as the version attribute:

..., integerNumber("version", Customer::getVersion, Customer::setVersion).as(version()), ...

Then, whenever a record is written the write operation will only succeed if the version number of the record has not been modified since it was last read by the application. Every time a new version of the record is successfully written to the database, the record version number will be automatically incremented.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	VersionedRecordExtension.AttributeTags
static class	VersionedRecordExtension.Builder

Method Summary

Modifier and Type	Method and Description
WriteModification	beforeWrite(Map<String,AttributeValue> item, OperationContext operationContext, TableMetadata tableMetadata) This hook is called just before an operation is going to write data to the database.
static VersionedRecordExtension.Builder	builder()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface software.amazon.awssdk.enhanced.dynamodb.DynamoDbEnhancedClientExtension

afterRead

Method Detail

builder

public static VersionedRecordExtension.Builder builder()

beforeWrite

public WriteModification beforeWrite(Map<String,AttributeValue> item,
                                     OperationContext operationContext,
                                     TableMetadata tableMetadata)

Description copied from interface: DynamoDbEnhancedClientExtension

This hook is called just before an operation is going to write data to the database. The extension that implements this method can choose to transform the item itself, or add a condition to the write operation or both.

Specified by:

beforeWrite in interface DynamoDbEnhancedClientExtension

Parameters:

item - The item that is about to be written.

operationContext - The context under which the operation to be modified is taking place.

tableMetadata - The structure of the table.

Returns:

A WriteModification object that can alter the behavior of the write operation.