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martinKindallzoewangg
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L-Applin
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EnumAttributeConverter: enums can be identified by toString() or name(). toString() is the default for backward compatibility (#3971)
Co-authored-by: Zoe Wang <[email protected]>
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‎.changes/next-release/bugfix-AmazonDynamoDB-2bb1833.json

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{
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"category": "Amazon DynamoDB",
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"contributor": "martinKindall",
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"type": "bugfix",
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"description": "Created static method EnumAttributeConverter::createWithNameAsKeys which creates a converter based on the Enum::name method to identify enums, rather than Enum::toString. This is preferable because Enum::name is final and cannot be overwritten, as opposed to Enum::toString. EnumAttributeConverter::create is kept as it is, for backward compatibility."
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}

‎services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/DefaultAttributeConverterProvider.java

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import software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.DocumentAttributeConverter;
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import software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.DoubleAttributeConverter;
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import software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.DurationAttributeConverter;
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import software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.EnumAttributeConverter;
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import software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.FloatAttributeConverter;
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import software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.InstantAsStringAttributeConverter;
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import software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.IntegerAttributeConverter;

‎services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/EnumAttributeConverter.java

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/*
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* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License").
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* You may not use this file except in compliance with the License.
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* A copy of the License is located at
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*
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* http://aws.amazon.com/apache2.0
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*
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* or in the "license" file accompanying this file. This file is distributed
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* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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* express or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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package software.amazon.awssdk.enhanced.dynamodb;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.LinkedHashMap;
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import java.util.Map;
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import java.util.function.Function;
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import software.amazon.awssdk.annotations.SdkPublicApi;
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import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
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import software.amazon.awssdk.utils.Validate;
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/**
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* A converter between an {@link Enum} and {@link AttributeValue}.
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*
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* <p>
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* This stores values in DynamoDB as a string.
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*
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* <p>
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* Use EnumAttributeConverter::create in order to use Enum::toString as the enum identifier
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*
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* <p>
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* Use EnumAttributeConverter::createWithNameAsKeys in order to use Enum::name as the enum identifier
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*
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* <p>
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* This can be created via {@link #create(Class)}.
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*/
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@SdkPublicApi
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public final class EnumAttributeConverter<T extends Enum<T>> implements AttributeConverter<T> {
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private final Class<T> enumClass;
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private final Map<String, T> enumValueMap;
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private final Function<T, String> keyExtractor;
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private EnumAttributeConverter(Class<T> enumClass, Function<T, String> keyExtractor) {
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this.enumClass = enumClass;
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this.keyExtractor = keyExtractor;
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Map<String, T> mutableEnumValueMap = new LinkedHashMap<>();
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Arrays.stream(enumClass.getEnumConstants())
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.forEach(enumConstant -> mutableEnumValueMap.put(keyExtractor.apply(enumConstant), enumConstant));
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this.enumValueMap = Collections.unmodifiableMap(mutableEnumValueMap);
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}
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/**
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* Creates an EnumAttributeConverter for an {@link Enum}.
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*
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* <p>
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* Uses Enum::toString as the enum identifier.
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*
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* @param enumClass The enum class to be used
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* @return an EnumAttributeConverter
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* @param <T> the enum subclass
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*/
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public static <T extends Enum<T>> EnumAttributeConverter<T> create(Class<T> enumClass) {
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return new EnumAttributeConverter<>(enumClass, Enum::toString);
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}
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/**
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* Creates an EnumAttributeConverter for an {@link Enum}.
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*
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* <p>
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* Uses Enum::name as the enum identifier.
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*
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* @param enumClass The enum class to be used
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* @return an EnumAttributeConverter
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* @param <T> the enum subclass
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*/
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public static <T extends Enum<T>> EnumAttributeConverter<T> createWithNameAsKeys(Class<T> enumClass) {
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return new EnumAttributeConverter<>(enumClass, Enum::name);
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}
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/**
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* Returns the proper {@link AttributeValue} for the given enum type.
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*
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* @param input the enum type to be converted
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* @return AttributeValue
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*/
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@Override
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public AttributeValue transformFrom(T input) {
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return AttributeValue.builder().s(keyExtractor.apply(input)).build();
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}
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/**
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* Returns the proper enum type for the given {@link AttributeValue} input.
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*
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* @param input the AttributeValue to be converted
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* @return an enum type
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*/
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@Override
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public T transformTo(AttributeValue input) {
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Validate.isTrue(input.s() != null, "Cannot convert non-string value to enum.");
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T returnValue = enumValueMap.get(input.s());
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if (returnValue == null) {
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throw new IllegalArgumentException(String.format("Unable to convert string value '%s' to enum type '%s'",
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input.s(), enumClass));
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}
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return returnValue;
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}
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/**
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* Returns the {@link EnhancedType} of the converter.
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*
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* @return EnhancedType
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*/
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@Override
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public EnhancedType<T> type() {
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return EnhancedType.of(enumClass);
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}
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/**
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* Returns the {@link AttributeValueType} of the converter.
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*
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* @return AttributeValueType
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*/
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@Override
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public AttributeValueType attributeValueType() {
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return AttributeValueType.S;
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}
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}

‎services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/converter/attribute/EnumAttributeConverter.java

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‎services-custom/dynamodb-enhanced/src/test/java/software/amazon/awssdk/enhanced/dynamodb/converters/attribute/EnumAttributeConverterTest.java

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/*
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* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License").
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* You may not use this file except in compliance with the License.
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* A copy of the License is located at
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*
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* http://aws.amazon.com/apache2.0
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*
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* or in the "license" file accompanying this file. This file is distributed
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* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
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* express or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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package software.amazon.awssdk.enhanced.dynamodb.converters.attribute;
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import org.junit.jupiter.api.Test;
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import software.amazon.awssdk.enhanced.dynamodb.EnumAttributeConverter;
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import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
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import static org.assertj.core.api.Assertions.assertThat;
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public class EnumAttributeConverterTest {
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@Test
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public void transformFromDefault_returnsToString() {
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EnumAttributeConverter<Vehicle> vehicleConverter = EnumAttributeConverter.create(Vehicle.class);
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AttributeValue attribute = vehicleConverter.transformFrom(Vehicle.TRUCK);
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assertThat(attribute.s()).isEqualTo("TRUCK");
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}
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@Test
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public void transformToDefault_returnsEnum() {
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EnumAttributeConverter<Vehicle> vehicleConverter = EnumAttributeConverter.create(Vehicle.class);
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Vehicle bike = vehicleConverter.transformTo(AttributeValue.fromS("BIKE"));
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assertThat(bike).isEqualTo(Vehicle.BIKE);
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}
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@Test
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public void transformFromDefault_returnsToString_2() {
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EnumAttributeConverter<Animal> animalConverter = EnumAttributeConverter.create(Animal.class);
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AttributeValue attribute = animalConverter.transformFrom(Animal.CAT);
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assertThat(attribute.s()).isEqualTo("I am a Cat!");
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}
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@Test
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public void transformToDefault_returnsEnum_2() {
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EnumAttributeConverter<Animal> animalConverter = EnumAttributeConverter.create(Animal.class);
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Animal dog = animalConverter.transformTo(AttributeValue.fromS("I am a Dog!"));
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assertThat(dog).isEqualTo(Animal.DOG);
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}
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@Test
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public void transformFromWithNames_returnsName() {
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EnumAttributeConverter<Person> personConverter = EnumAttributeConverter.createWithNameAsKeys(Person.class);
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AttributeValue attribute = personConverter.transformFrom(Person.JANE);
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assertThat(attribute.s()).isEqualTo("JANE");
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assertThat(Person.JANE.toString()).isEqualTo("I am a cool person");
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}
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@Test
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public void transformToWithNames_returnsEnum() {
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EnumAttributeConverter<Person> personConverter = EnumAttributeConverter.createWithNameAsKeys(Person.class);
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Person john = personConverter.transformTo(AttributeValue.fromS("JOHN"));
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assertThat(Person.JOHN.toString()).isEqualTo("I am a cool person");
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assertThat(john).isEqualTo(Person.JOHN);
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}
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private static enum Vehicle {
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CAR,
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BIKE,
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TRUCK
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}
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private static enum Animal {
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DOG,
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CAT;
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@Override
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public String toString() {
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switch (this) {
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case DOG:
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return "I am a Dog!";
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case CAT:
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return "I am a Cat!";
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default:
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return null;
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}
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}
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}
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private static enum Person {
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JOHN,
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JANE;
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@Override
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public String toString() {
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return "I am a cool person";
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}
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}
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}

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