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Support AutoGeneratedTimestamp and UpdateBehavior annotation in nested objects #6109

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befc5cd
Added support for @DynamoDbAutoGeneratedTimestampAttribute and @Dynam…
roamariei May 15, 2025
71c57d5
fixed checkstyle and used StringBuilder
roamariei Jun 6, 2025
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6 changes: 6 additions & 0 deletions .changes/next-release/feature-AmazonDynamoDBEnhancedClient-96aff9e.json
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@@ -0,0 +1,6 @@
{
"type": "feature",
"category": "Amazon DynamoDB Enhanced Client",
"contributor": "",
"description": "Added support for @DynamoDbAutoGeneratedTimestampAttribute and @DynamoDbUpdateBehavior on attributes within nested objects. The @DynamoDbUpdateBehavior annotation will only take effect for nested attributes when using IgnoreNullsMode.SCALAR_ONLY."
}
177 changes: 168 additions & 9 deletions ...are/amazon/awssdk/enhanced/dynamodb/extensions/AutoGeneratedTimestampRecordExtension.java
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Expand Up @@ -15,13 +15,20 @@

package software.amazon.awssdk.enhanced.dynamodb.extensions;

import static software.amazon.awssdk.enhanced.dynamodb.internal.EnhancedClientUtils.getNestedSchema;
import static software.amazon.awssdk.enhanced.dynamodb.internal.operations.UpdateItemOperation.NESTED_OBJECT_UPDATE;

import java.time.Clock;
import java.time.Instant;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.function.Consumer;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import software.amazon.awssdk.annotations.NotThreadSafe;
import software.amazon.awssdk.annotations.SdkPublicApi;
import software.amazon.awssdk.annotations.ThreadSafe;
Expand All @@ -30,6 +37,7 @@
import software.amazon.awssdk.enhanced.dynamodb.DynamoDbEnhancedClientExtension;
import software.amazon.awssdk.enhanced.dynamodb.DynamoDbExtensionContext;
import software.amazon.awssdk.enhanced.dynamodb.EnhancedType;
import software.amazon.awssdk.enhanced.dynamodb.TableSchema;
import software.amazon.awssdk.enhanced.dynamodb.mapper.StaticAttributeTag;
import software.amazon.awssdk.enhanced.dynamodb.mapper.StaticTableMetadata;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
Expand Down Expand Up @@ -64,13 +72,17 @@
* <p>
* Every time a new update of the record is successfully written to the database, the timestamp at which it was modified will
* be automatically updated. This extension applies the conversions as defined in the attribute convertor.
* The implementation handles both flattened nested parameters (identified by keys separated with
* {@code "_NESTED_ATTR_UPDATE_"}) and entire nested maps or lists, ensuring consistent behavior across both representations.
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Should we clarify here the difference in null value handling?

* The same timestamp value is used for both top-level attributes and all applicable nested fields.
*/
@SdkPublicApi
@ThreadSafe
public final class AutoGeneratedTimestampRecordExtension implements DynamoDbEnhancedClientExtension {
private static final String CUSTOM_METADATA_KEY = "AutoGeneratedTimestampExtension:AutoGeneratedTimestampAttribute";
private static final AutoGeneratedTimestampAttribute
AUTO_GENERATED_TIMESTAMP_ATTRIBUTE = new AutoGeneratedTimestampAttribute();
private static final Pattern NESTED_OBJECT_PATTERN = Pattern.compile(NESTED_OBJECT_UPDATE);
private final Clock clock;

private AutoGeneratedTimestampRecordExtension() {
Expand Down Expand Up @@ -126,26 +138,173 @@ public static AutoGeneratedTimestampRecordExtension create() {
*/
@Override
public WriteModification beforeWrite(DynamoDbExtensionContext.BeforeWrite context) {
Map<String, AttributeValue> itemToTransform = new HashMap<>(context.items());

Map<String, AttributeValue> updatedItems = new HashMap<>();
Instant currentInstant = clock.instant();

Collection<String> customMetadataObject = context.tableMetadata()
.customMetadataObject(CUSTOM_METADATA_KEY, Collection.class).orElse(null);
itemToTransform.forEach((key, value) -> {
if (value.hasM() && value.m() != null) {
Optional<? extends TableSchema<?>> nestedSchema = getNestedSchema(context.tableSchema(), key);
if (nestedSchema.isPresent()) {
Map<String, AttributeValue> processed = processNestedObject(value.m(), nestedSchema.get(), currentInstant);
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Is there a possible performance degradation for deeply nested records?

updatedItems.put(key, AttributeValue.builder().m(processed).build());
}
} else if (value.hasL() && !value.l().isEmpty() && value.l().get(0).hasM()) {
TableSchema<?> elementListSchema = getTableSchemaForListElement(context.tableSchema(), key);

List<AttributeValue> updatedList = value.l()
.stream()
.map(listItem -> listItem.hasM() ?
AttributeValue.builder()
.m(processNestedObject(listItem.m(),
elementListSchema,
currentInstant))
.build() : listItem)
.collect(Collectors.toList());
updatedItems.put(key, AttributeValue.builder().l(updatedList).build());
}
});

Map<String, TableSchema<?>> stringTableSchemaMap = resolveSchemasPerPath(itemToTransform, context.tableSchema());

stringTableSchemaMap.forEach((path, schema) -> {
Collection<String> customMetadataObject = schema.tableMetadata()
.customMetadataObject(CUSTOM_METADATA_KEY, Collection.class)
.orElse(null);

if (customMetadataObject != null) {
customMetadataObject.forEach(
key -> insertTimestampInItemToTransform(updatedItems, reconstructCompositeKey(path, key),
schema.converterForAttribute(key), currentInstant));
}
});

if (customMetadataObject == null) {
if (updatedItems.isEmpty()) {
return WriteModification.builder().build();
}
Map<String, AttributeValue> itemToTransform = new HashMap<>(context.items());
customMetadataObject.forEach(
key -> insertTimestampInItemToTransform(itemToTransform, key,
context.tableSchema().converterForAttribute(key)));

itemToTransform.putAll(updatedItems);

return WriteModification.builder()
.transformedItem(Collections.unmodifiableMap(itemToTransform))
.build();
}

private TableSchema<?> getTableSchemaForListElement(TableSchema<?> rootSchema, String key) {
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Some of these private utility functions seem generic to nested records rather than to auto generated timestamps - I'm not against keeping them here since it limits the scope and I'm not all that familiar with this library - but would it make sense to move these to a utility?

TableSchema<?> listElementSchema;
try {
if (!key.contains(NESTED_OBJECT_UPDATE)) {
listElementSchema = TableSchema.fromClass(
Class.forName(rootSchema.converterForAttribute(key).type().rawClassParameters().get(0).rawClass().getName()));
} else {
String[] parts = NESTED_OBJECT_PATTERN.split(key);
TableSchema<?> currentSchema = rootSchema;

for (int i = 0; i < parts.length - 1; i++) {
Optional<? extends TableSchema<?>> nestedSchema = getNestedSchema(currentSchema, parts[i]);
if (nestedSchema.isPresent()) {
currentSchema = nestedSchema.get();
}
}
String attributeName = parts[parts.length - 1];
listElementSchema = TableSchema.fromClass(
Class.forName(currentSchema.converterForAttribute(attributeName)
.type().rawClassParameters().get(0).rawClass().getName()));
}
} catch (ClassNotFoundException e) {
throw new IllegalArgumentException("Class not found for field name: " + key, e);
}
return listElementSchema;
}

private Map<String, TableSchema<?>> resolveSchemasPerPath(Map<String, AttributeValue> attributesToSet,
TableSchema<?> rootSchema) {
Map<String, TableSchema<?>> schemaMap = new HashMap<>();
schemaMap.put("", rootSchema);

for (String key : attributesToSet.keySet()) {
String[] parts = NESTED_OBJECT_PATTERN.split(key);

StringBuilder pathBuilder = new StringBuilder();
TableSchema<?> currentSchema = rootSchema;

for (int i = 0; i < parts.length - 1; i++) {
if (pathBuilder.length() > 0) {
pathBuilder.append(".");
}
pathBuilder.append(parts[i]);

String path = pathBuilder.toString();

if (!schemaMap.containsKey(path)) {
Optional<? extends TableSchema<?>> nestedSchema = getNestedSchema(currentSchema, parts[i]);
if (nestedSchema.isPresent()) {
schemaMap.put(path, nestedSchema.get());
currentSchema = nestedSchema.get();
}
} else {
currentSchema = schemaMap.get(path);
}
}
}
return schemaMap;
}

private static String reconstructCompositeKey(String path, String attributeName) {
if (path == null || path.isEmpty()) {
return attributeName;
}
return String.join(NESTED_OBJECT_UPDATE, path.split("\\."))
+ NESTED_OBJECT_UPDATE + attributeName;
}

private Map<String, AttributeValue> processNestedObject(Map<String, AttributeValue> nestedMap, TableSchema<?> nestedSchema,
Instant currentInstant) {
Map<String, AttributeValue> updatedNestedMap = new HashMap<>(nestedMap);
Collection<String> customMetadataObject = nestedSchema.tableMetadata()
.customMetadataObject(CUSTOM_METADATA_KEY, Collection.class).orElse(null);

if (customMetadataObject != null) {
customMetadataObject.forEach(
key -> insertTimestampInItemToTransform(updatedNestedMap, String.valueOf(key),
nestedSchema.converterForAttribute(key), currentInstant));
}

nestedMap.forEach((nestedKey, nestedValue) -> {
if (nestedValue.hasM()) {
updatedNestedMap.put(nestedKey,
AttributeValue.builder().m(processNestedObject(nestedValue.m(), nestedSchema,
currentInstant)).build());
} else if (nestedValue.hasL() && !nestedValue.l().isEmpty()
&& nestedValue.l().get(0).hasM()) {
try {
TableSchema<?> listElementSchema = TableSchema.fromClass(
Class.forName(nestedSchema.converterForAttribute(nestedKey)
.type().rawClassParameters().get(0).rawClass().getName()));
List<AttributeValue> updatedList = nestedValue
.l()
.stream()
.map(listItem -> listItem.hasM() ?
AttributeValue.builder()
.m(processNestedObject(listItem.m(),
listElementSchema,
currentInstant)).build() : listItem)
.collect(Collectors.toList());
updatedNestedMap.put(nestedKey, AttributeValue.builder().l(updatedList).build());
} catch (ClassNotFoundException e) {
throw new IllegalArgumentException("Class not found for field name: " + nestedKey, e);
}
}
});
return updatedNestedMap;
}

private void insertTimestampInItemToTransform(Map<String, AttributeValue> itemToTransform,
String key,
AttributeConverter converter) {
itemToTransform.put(key, converter.transformFrom(clock.instant()));
AttributeConverter converter,
Instant instant) {
itemToTransform.put(key, converter.transformFrom(instant));
}

/**
Expand Down
11 changes: 11 additions & 0 deletions .../src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/EnhancedClientUtils.java
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Expand Up @@ -204,4 +204,15 @@ public static <T> List<T> getItemsFromSupplier(List<Supplier<T>> itemSupplierLis
public static boolean isNullAttributeValue(AttributeValue attributeValue) {
return attributeValue.nul() != null && attributeValue.nul();
}

/**
* Retrieves the {@link TableSchema} for a nested attribute within the given parent schema.
*
* @param parentSchema the schema of the parent bean class
* @param attributeName the name of the nested attribute
* @return an {@link Optional} containing the nested attribute's {@link TableSchema}, or empty if unavailable
*/
public static Optional<? extends TableSchema<?>> getNestedSchema(TableSchema<?> parentSchema, String attributeName) {
return parentSchema.converterForAttribute(attributeName).type().tableSchema();
}
}
7 changes: 3 additions & 4 deletions ...ava/software/amazon/awssdk/enhanced/dynamodb/internal/operations/UpdateItemOperation.java
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Expand Up @@ -131,8 +131,7 @@ public UpdateItemRequest generateRequest(TableSchema<T> tableSchema,

Map<String, AttributeValue> keyAttributes = filterMap(itemMap, entry -> primaryKeys.contains(entry.getKey()));
Map<String, AttributeValue> nonKeyAttributes = filterMap(itemMap, entry -> !primaryKeys.contains(entry.getKey()));

Expression updateExpression = generateUpdateExpressionIfExist(tableMetadata, transformation, nonKeyAttributes);
Expression updateExpression = generateUpdateExpressionIfExist(tableSchema, transformation, nonKeyAttributes);
Expression conditionExpression = generateConditionExpressionIfExist(transformation, request);

Map<String, String> expressionNames = coalesceExpressionNames(updateExpression, conditionExpression);
Expand Down Expand Up @@ -275,7 +274,7 @@ public TransactWriteItem generateTransactWriteItem(TableSchema<T> tableSchema, O
* if there are attributes to be updated (most likely). If both exist, they are merged and the code generates a final
* Expression that represent the result.
*/
private Expression generateUpdateExpressionIfExist(TableMetadata tableMetadata,
private Expression generateUpdateExpressionIfExist(TableSchema<T> tableSchema,
WriteModification transformation,
Map<String, AttributeValue> attributes) {
UpdateExpression updateExpression = null;
Expand All @@ -284,7 +283,7 @@ private Expression generateUpdateExpressionIfExist(TableMetadata tableMetadata,
}
if (!attributes.isEmpty()) {
List<String> nonRemoveAttributes = UpdateExpressionConverter.findAttributeNames(updateExpression);
UpdateExpression operationUpdateExpression = operationExpression(attributes, tableMetadata, nonRemoveAttributes);
UpdateExpression operationUpdateExpression = operationExpression(attributes, tableSchema, nonRemoveAttributes);
if (updateExpression == null) {
updateExpression = operationUpdateExpression;
} else {
Expand Down
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