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Add support for flattening prefixes to DynamoDB fields
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This makes enables clients to avoid conflicts if flattened schemas happen
to share a field name. The design maintains backwards compatibility with
existing codebases by requiring that users opt-in to this behavior
explicitly. While this increases the mental overhead there is a design
to enable the auto-prefixing as the default behavior when creating the
mapper. However, that is outside of the scope of this current implementation.
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@akiesler
Andy Kiesler authored and akiesler committed Sep 23, 2024
1 parent 8a3feed commit 9a8bbd7
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Showing 10 changed files with 318 additions and 6 deletions.
6 changes: 6 additions & 0 deletions .changes/next-release/feature-AmazonDynamoDB-3f6308a.json
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{
"category": "Amazon DynamoDB",
"contributor": "kiesler",
"type": "feature",
"description": "Support optional prefix for `@DynamoDbFlatten` fields"
}
11 changes: 10 additions & 1 deletion ...hanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/mapper/BeanTableSchema.java
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Expand Up @@ -203,7 +203,8 @@ private static <T> StaticTableSchema<T> createStaticTableSchema(Class<T> beanCla
if (dynamoDbFlatten != null) {
builder.flatten(TableSchema.fromClass(propertyDescriptor.getReadMethod().getReturnType()),
getterForProperty(propertyDescriptor, beanClass),
setterForProperty(propertyDescriptor, beanClass));
setterForProperty(propertyDescriptor, beanClass),
getFlattenedPrefix(propertyDescriptor, dynamoDbFlatten));
} else {
AttributeConfiguration attributeConfiguration =
resolveAttributeConfiguration(propertyDescriptor);
Expand All @@ -225,6 +226,14 @@ private static <T> StaticTableSchema<T> createStaticTableSchema(Class<T> beanCla
return builder.build();
}

private static String getFlattenedPrefix(PropertyDescriptor propertyDescriptor, DynamoDbFlatten dynamoDbFlatten) {
boolean useAutoPrefix = DynamoDbFlatten.AUTO_PREFIX.equals(dynamoDbFlatten.prefix());
if (!useAutoPrefix) {
return dynamoDbFlatten.prefix();
}
return attributeNameForProperty(propertyDescriptor) + ".";
}

private static AttributeConfiguration resolveAttributeConfiguration(PropertyDescriptor propertyDescriptor) {
boolean shouldPreserveEmptyObject = getPropertyAnnotation(propertyDescriptor,
DynamoDbPreserveEmptyObject.class) != null;
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11 changes: 10 additions & 1 deletion ...d/src/main/java/software/amazon/awssdk/enhanced/dynamodb/mapper/ImmutableTableSchema.java
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Expand Up @@ -201,7 +201,8 @@ private static <T, B> StaticImmutableTableSchema<T, B> createStaticImmutableTab
if (dynamoDbFlatten != null) {
builder.flatten(TableSchema.fromClass(propertyDescriptor.getter().getReturnType()),
getterForProperty(propertyDescriptor, immutableClass),
setterForProperty(propertyDescriptor, builderClass));
setterForProperty(propertyDescriptor, builderClass),
getFlattenedPrefix(propertyDescriptor, dynamoDbFlatten));
} else {
AttributeConfiguration beanAttributeConfiguration = resolveAttributeConfiguration(propertyDescriptor);
ImmutableAttribute.Builder<T, B, ?> attributeBuilder =
Expand All @@ -225,6 +226,14 @@ private static <T, B> StaticImmutableTableSchema<T, B> createStaticImmutableTab
return builder.build();
}

private static String getFlattenedPrefix(ImmutablePropertyDescriptor propertyDescriptor, DynamoDbFlatten dynamoDbFlatten) {
boolean useAutoPrefix = DynamoDbFlatten.AUTO_PREFIX.equals(dynamoDbFlatten.prefix());
if (!useAutoPrefix) {
return dynamoDbFlatten.prefix();
}
return attributeNameForProperty(propertyDescriptor) + ".";
}

private static List<AttributeConverterProvider> createConverterProvidersFromAnnotation(Class<?> immutableClass,
DynamoDbImmutable dynamoDbImmutable) {

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48 changes: 48 additions & 0 deletions ...ain/java/software/amazon/awssdk/enhanced/dynamodb/mapper/annotations/DynamoDbFlatten.java
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Expand Up @@ -25,14 +25,62 @@
* This annotation is used to flatten all the attributes of a separate DynamoDb bean that is stored in the current bean
* object and add them as top level attributes to the record that is read and written to the database. The target bean
* to flatten must be specified as part of this annotation.
* The flattening behavior can be controlled by the prefix value of the annotation.
* The default behavior is that no prefix is applied (this is done for backwards compatability).
* If a String value is supplied then that is prefixed to the attribute names.
* If a value of {@code DynamoDbFlatten.AUTO_PREFIX} is supplied then the attribute name of the flattened bean appended
* with a period ('.') is used as the prefix.
*
* Example, given the following classes:
* <pre>{@code
* @DynamoDbBean
* public class Flattened {
* String getValue();
* }
*
* @DynamoDbBean
* public class Record {
* @DynamoDbFlatten
* Flattened getNoPrefix(); // translates to attribute 'value'
* @DynamoDbFlatten(prefix = "prefix-")
* Flattened getExplicitPrefix(); // translates to attribute 'prefix-value'
* @DynamoDbFlatten(prefix = DynamoDbFlatten.AUTO_PREFIX)
* Flattened getInferredPrefix(); // translates to attribute 'inferredPrefix.value'
* @DynamoDbAttribute("custom")
* @DynamoDbFlatten(prefix = DynamoDbFlatten.AUTO_PREFIX)
* Flattened getFlattened(); // translates to attribute 'custom.value'
* }
*}</pre>
* They would be mapped as such:
* <pre>{@code
* {
* "value": {"S": "..."},
* "prefix-value": {"S": "..."},
* "inferredPrefix.value": {"S": "..."},
* "custom.value": {"S": "..."},
* }
* }</pre>
*/
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@SdkPublicApi
public @interface DynamoDbFlatten {
/**
* Values used to denote that the mapper should append the current attribute name to flattened fields.
*/
String AUTO_PREFIX = "AUTO_PREFIX";

/**
* @deprecated This is no longer used, the class type of the attribute will be used instead.
*/
@Deprecated
Class<?> dynamoDbBeanClass() default Object.class;

/**
* Optional prefix to append to the flattened bean attributes in the schema.
* Specifying a value of {@code DynamoDbFlatten.AUTO_PREFIX} will use the annotated methods attribute name as the
* prefix.
* default: {@code ""} (No prefix)
*/
String prefix() default "";
}
51 changes: 49 additions & 2 deletions ...ed/src/test/java/software/amazon/awssdk/enhanced/dynamodb/mapper/BeanTableSchemaTest.java
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Expand Up @@ -37,6 +37,7 @@
import java.util.Optional;
import org.junit.Rule;
import org.junit.Test;
import org.junit.jupiter.api.Assertions;
import org.junit.rules.ExpectedException;
import org.junit.runner.RunWith;
import org.mockito.junit.MockitoJUnitRunner;
Expand All @@ -54,6 +55,7 @@
import software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans.EnumBean;
import software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans.ExtendedBean;
import software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans.FlattenedBeanBean;
import software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans.FlattenedBeanImmutable;
import software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans.FlattenedImmutableBean;
import software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans.IgnoredAttributeBean;
import software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans.InvalidBean;
Expand Down Expand Up @@ -178,18 +180,57 @@ public void dynamoDbAttribute_remapsAttributeName() {
@Test
public void dynamoDbFlatten_correctlyFlattensBeanAttributes() {
BeanTableSchema<FlattenedBeanBean> beanTableSchema = BeanTableSchema.create(FlattenedBeanBean.class);

assertThat(beanTableSchema.attributeNames(), containsInAnyOrder("id", "attribute1", "attribute2",
"prefix-attribute2", "autoPrefixBean.attribute2", "custom.attribute2"));

AbstractBean abstractBean = new AbstractBean();
abstractBean.setAttribute2("two");
FlattenedBeanBean flattenedBeanBean = new FlattenedBeanBean();
flattenedBeanBean.setId("id-value");
flattenedBeanBean.setAttribute1("one");
flattenedBeanBean.setAbstractBean(abstractBean);
flattenedBeanBean.setExplicitPrefixBean(abstractBean);
flattenedBeanBean.setAutoPrefixBean(abstractBean);
flattenedBeanBean.setCustomPrefixBean(abstractBean);

Map<String, AttributeValue> itemMap = beanTableSchema.itemToMap(flattenedBeanBean, false);
assertThat(itemMap.size(), is(3));
assertThat(itemMap.size(), is(6));
assertThat(itemMap, hasEntry("id", stringValue("id-value")));
assertThat(itemMap, hasEntry("attribute1", stringValue("one")));
assertThat(itemMap, hasEntry("attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("prefix-attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("autoPrefixBean.attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("custom.attribute2", stringValue("two")));
}

@Test
public void dynamoDbFlatten_correctlyGetFlattenedBeanAttributes() {
BeanTableSchema<FlattenedBeanBean> tableSchema = BeanTableSchema.create(FlattenedBeanBean.class);

AbstractBean abstractBean = new AbstractBean();
abstractBean.setAttribute2("two");
AbstractBean explicitPrefixBean = new AbstractBean();
explicitPrefixBean.setAttribute2("three");
AbstractBean autoPrefixBean = new AbstractBean();
autoPrefixBean.setAttribute2("four");
AbstractBean customPrefixBean = new AbstractBean();
customPrefixBean.setAttribute2("five");

FlattenedBeanBean bean = new FlattenedBeanBean();
bean.setId("id-value");
bean.setAttribute1("one");
bean.setAbstractBean(abstractBean);
bean.setExplicitPrefixBean(explicitPrefixBean);
bean.setAutoPrefixBean(autoPrefixBean);
bean.setCustomPrefixBean(customPrefixBean);

assertThat(tableSchema.attributeValue(bean, "id"), equalTo(stringValue("id-value")));
assertThat(tableSchema.attributeValue(bean, "attribute1"), equalTo(stringValue("one")));
assertThat(tableSchema.attributeValue(bean, "attribute2"), equalTo(stringValue("two")));
assertThat(tableSchema.attributeValue(bean, "prefix-attribute2"), equalTo(stringValue("three")));
assertThat(tableSchema.attributeValue(bean, "autoPrefixBean.attribute2"), equalTo(stringValue("four")));
assertThat(tableSchema.attributeValue(bean, "custom.attribute2"), equalTo(stringValue("five")));
}

@Test
Expand Down Expand Up @@ -248,12 +289,18 @@ public void dynamoDbFlatten_correctlyFlattensImmutableAttributes() {
flattenedImmutableBean.setId("id-value");
flattenedImmutableBean.setAttribute1("one");
flattenedImmutableBean.setAbstractImmutable(abstractImmutable);
flattenedImmutableBean.setExplicitPrefixImmutable(abstractImmutable);
flattenedImmutableBean.setAutoPrefixImmutable(abstractImmutable);
flattenedImmutableBean.setCustomPrefixImmutable(abstractImmutable);

Map<String, AttributeValue> itemMap = beanTableSchema.itemToMap(flattenedImmutableBean, false);
assertThat(itemMap.size(), is(3));
assertThat(itemMap.size(), is(6));
assertThat(itemMap, hasEntry("id", stringValue("id-value")));
assertThat(itemMap, hasEntry("attribute1", stringValue("one")));
assertThat(itemMap, hasEntry("attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("prefix-attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("autoPrefixImmutable.attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("custom.attribute2", stringValue("two")));
}

@Test
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58 changes: 56 additions & 2 deletions ...c/test/java/software/amazon/awssdk/enhanced/dynamodb/mapper/ImmutableTableSchemaTest.java
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Expand Up @@ -17,6 +17,9 @@

import static java.util.Collections.singletonMap;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.contains;
import static org.hamcrest.Matchers.containsInAnyOrder;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.hasEntry;
import static org.hamcrest.Matchers.is;
import static software.amazon.awssdk.enhanced.dynamodb.internal.AttributeValues.nullAttributeValue;
Expand All @@ -25,6 +28,8 @@
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Collectors;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans.AbstractBean;
import software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans.AbstractImmutable;
Expand Down Expand Up @@ -213,37 +218,86 @@ public void documentImmutable_map_correctlyMapsImmutableAttributes() {
public void dynamoDbFlatten_correctlyFlattensBeanAttributes() {
ImmutableTableSchema<FlattenedBeanImmutable> tableSchema =
ImmutableTableSchema.create(FlattenedBeanImmutable.class);

assertThat(tableSchema.attributeNames(), containsInAnyOrder("id", "attribute1", "attribute2",
"prefix-attribute2", "autoPrefixBean.attribute2", "custom.attribute2"));

AbstractBean abstractBean = new AbstractBean();
abstractBean.setAttribute2("two");
FlattenedBeanImmutable flattenedBeanImmutable =
new FlattenedBeanImmutable.Builder().setId("id-value")
.setAttribute1("one")
.setAbstractBean(abstractBean)
.setExplicitPrefixBean(abstractBean)
.setAutoPrefixBean(abstractBean)
.setCustomPrefixBean(abstractBean)
.build();

Map<String, AttributeValue> itemMap = tableSchema.itemToMap(flattenedBeanImmutable, false);
assertThat(itemMap.size(), is(3));
assertThat(itemMap.size(), is(6));
assertThat(itemMap, hasEntry("id", stringValue("id-value")));
assertThat(itemMap, hasEntry("attribute1", stringValue("one")));
assertThat(itemMap, hasEntry("attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("prefix-attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("autoPrefixBean.attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("custom.attribute2", stringValue("two")));
}

@Test
public void dynamoDbFlatten_correctlyFlattensImmutableAttributes() {
ImmutableTableSchema<FlattenedImmutableImmutable> tableSchema =
ImmutableTableSchema.create(FlattenedImmutableImmutable.class);

assertThat(tableSchema.attributeNames(), containsInAnyOrder("id", "attribute1", "attribute2",
"prefix-attribute2", "autoPrefixImmutable.attribute2", "custom.attribute2"));

AbstractImmutable abstractImmutable = AbstractImmutable.builder().attribute2("two").build();
FlattenedImmutableImmutable FlattenedImmutableImmutable =
new FlattenedImmutableImmutable.Builder().setId("id-value")
.setAttribute1("one")
.setAbstractImmutable(abstractImmutable)
.setExplicitPrefixImmutable(abstractImmutable)
.setAutoPrefixImmutable(abstractImmutable)
.setCustomPrefixImmutable(abstractImmutable)
.build();

Map<String, AttributeValue> itemMap = tableSchema.itemToMap(FlattenedImmutableImmutable, false);
assertThat(itemMap.size(), is(3));
assertThat(itemMap.size(), is(6));
assertThat(itemMap, hasEntry("id", stringValue("id-value")));
assertThat(itemMap, hasEntry("attribute1", stringValue("one")));
assertThat(itemMap, hasEntry("attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("prefix-attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("autoPrefixImmutable.attribute2", stringValue("two")));
assertThat(itemMap, hasEntry("custom.attribute2", stringValue("two")));
}

@Test
public void dynamoDbFlatten_correctlyGetFlattenedBeanAttributes() {
ImmutableTableSchema<FlattenedBeanImmutable> tableSchema =
ImmutableTableSchema.create(FlattenedBeanImmutable.class);

AbstractBean abstractBean = new AbstractBean();
abstractBean.setAttribute2("two");
AbstractBean explicitPrefixBean = new AbstractBean();
explicitPrefixBean.setAttribute2("three");
AbstractBean autoPrefixBean = new AbstractBean();
autoPrefixBean.setAttribute2("four");
AbstractBean customPrefixBean = new AbstractBean();
customPrefixBean.setAttribute2("five");
FlattenedBeanImmutable bean = new FlattenedBeanImmutable.Builder().setId("id-value")
.setAttribute1("one")
.setAbstractBean(abstractBean)
.setExplicitPrefixBean(explicitPrefixBean)
.setAutoPrefixBean(autoPrefixBean)
.setCustomPrefixBean(customPrefixBean)
.build();

assertThat(tableSchema.attributeValue(bean, "id"), equalTo(stringValue("id-value")));
assertThat(tableSchema.attributeValue(bean, "attribute1"), equalTo(stringValue("one")));
assertThat(tableSchema.attributeValue(bean, "attribute2"), equalTo(stringValue("two")));
assertThat(tableSchema.attributeValue(bean, "prefix-attribute2"), equalTo(stringValue("three")));
assertThat(tableSchema.attributeValue(bean, "autoPrefixBean.attribute2"), equalTo(stringValue("four")));
assertThat(tableSchema.attributeValue(bean, "custom.attribute2"), equalTo(stringValue("five")));
}

@Test
Expand Down
29 changes: 29 additions & 0 deletions ...est/java/software/amazon/awssdk/enhanced/dynamodb/mapper/testbeans/FlattenedBeanBean.java
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Expand Up @@ -15,6 +15,7 @@

package software.amazon.awssdk.enhanced.dynamodb.mapper.testbeans;

import software.amazon.awssdk.enhanced.dynamodb.mapper.annotations.DynamoDbAttribute;
import software.amazon.awssdk.enhanced.dynamodb.mapper.annotations.DynamoDbBean;
import software.amazon.awssdk.enhanced.dynamodb.mapper.annotations.DynamoDbFlatten;
import software.amazon.awssdk.enhanced.dynamodb.mapper.annotations.DynamoDbPartitionKey;
Expand All @@ -24,6 +25,9 @@ public class FlattenedBeanBean {
private String id;
private String attribute1;
private AbstractBean abstractBean;
private AbstractBean explicitPrefixBean;
private AbstractBean autoPrefixBean;
private AbstractBean customPrefixBean;

@DynamoDbPartitionKey
public String getId() {
Expand All @@ -47,4 +51,29 @@ public AbstractBean getAbstractBean() {
public void setAbstractBean(AbstractBean abstractBean) {
this.abstractBean = abstractBean;
}

@DynamoDbFlatten(prefix = "prefix-")
public AbstractBean getExplicitPrefixBean() {
return explicitPrefixBean;
}
public void setExplicitPrefixBean(AbstractBean explicitPrefixBean) {
this.explicitPrefixBean = explicitPrefixBean;
}

@DynamoDbFlatten(prefix = DynamoDbFlatten.AUTO_PREFIX)
public AbstractBean getAutoPrefixBean() {
return autoPrefixBean;
}
public void setAutoPrefixBean(AbstractBean autoPrefixBean) {
this.autoPrefixBean = autoPrefixBean;
}

@DynamoDbAttribute("custom")
@DynamoDbFlatten(prefix = DynamoDbFlatten.AUTO_PREFIX)
public AbstractBean getCustomPrefixBean() {
return customPrefixBean;
}
public void setCustomPrefixBean(AbstractBean customPrefixBean) {
this.customPrefixBean = customPrefixBean;
}
}
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