Add support for DTO projections.

See: #2851
Original Pull Request: #2854

Author: mp911de

src/main/antora/modules/ROOT/pages/repositories/projections.adoc

@@ -1,4 +1,4 @@
-[[cassandra.projections]]
+[[redis.projections]]
 = Projections
 
 include::{commons}@data-commons::page$repositories/projections.adoc[leveloffset=+1]

src/main/java/org/springframework/data/redis/aot/RedisRuntimeHints.java

@@ -46,6 +46,7 @@
 import org.springframework.data.redis.core.index.IndexConfiguration;
 import org.springframework.data.redis.core.mapping.RedisMappingContext;
 import org.springframework.data.redis.listener.RedisMessageListenerContainer;
+import org.springframework.data.redis.repository.query.RedisPartTreeQuery;
 import org.springframework.data.redis.repository.query.RedisQueryCreator;
 import org.springframework.data.redis.repository.support.RedisRepositoryFactoryBean;
 import org.springframework.lang.Nullable;
@@ -106,15 +107,15 @@ public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader)
 						TypeReference.of(ReactiveClusterScriptingCommands.class),
 						TypeReference.of(ReactiveClusterGeoCommands.class),
 						TypeReference.of(ReactiveClusterHyperLogLogCommands.class), TypeReference.of(ReactiveRedisOperations.class),
-						TypeReference.of(ReactiveRedisConnectionFactory.class),
-						TypeReference.of(ReactiveRedisTemplate.class), TypeReference.of(RedisOperations.class),
-						TypeReference.of(RedisTemplate.class), TypeReference.of(StringRedisTemplate.class),
-						TypeReference.of(KeyspaceConfiguration.class), TypeReference.of(MappingConfiguration.class),
-						TypeReference.of(MappingRedisConverter.class), TypeReference.of(RedisConverter.class),
-						TypeReference.of(RedisCustomConversions.class), TypeReference.of(ReferenceResolver.class),
-						TypeReference.of(ReferenceResolverImpl.class), TypeReference.of(IndexConfiguration.class),
-						TypeReference.of(ConfigurableIndexDefinitionProvider.class), TypeReference.of(RedisMappingContext.class),
-						TypeReference.of(RedisRepositoryFactoryBean.class), TypeReference.of(RedisQueryCreator.class),
+						TypeReference.of(ReactiveRedisConnectionFactory.class), TypeReference.of(ReactiveRedisTemplate.class),
+						TypeReference.of(RedisOperations.class), TypeReference.of(RedisTemplate.class),
+						TypeReference.of(StringRedisTemplate.class), TypeReference.of(KeyspaceConfiguration.class),
+						TypeReference.of(MappingConfiguration.class), TypeReference.of(MappingRedisConverter.class),
+						TypeReference.of(RedisConverter.class), TypeReference.of(RedisCustomConversions.class),
+						TypeReference.of(ReferenceResolver.class), TypeReference.of(ReferenceResolverImpl.class),
+						TypeReference.of(IndexConfiguration.class), TypeReference.of(ConfigurableIndexDefinitionProvider.class),
+						TypeReference.of(RedisMappingContext.class), TypeReference.of(RedisRepositoryFactoryBean.class),
+						TypeReference.of(RedisQueryCreator.class), TypeReference.of(RedisPartTreeQuery.class),
 						TypeReference.of(MessageListener.class), TypeReference.of(RedisMessageListenerContainer.class),
 
 						TypeReference

src/main/java/org/springframework/data/redis/core/convert/MappingRedisConverter.java

@@ -16,8 +16,17 @@
 package org.springframework.data.redis.core.convert;
 
 import java.lang.reflect.Array;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Optional;
+import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -1046,6 +1055,11 @@ public IndexResolver getIndexResolver() {
 		return this.indexResolver;
 	}
 
+	@Override
+	public EntityInstantiators getEntityInstantiators() {
+		return entityInstantiators;
+	}
+
 	@Override
 	public ConversionService getConversionService() {
 		return this.conversionService;

src/main/java/org/springframework/data/redis/core/convert/RedisConverter.java

@@ -16,6 +16,7 @@
 package org.springframework.data.redis.core.convert;
 
 import org.springframework.data.convert.EntityConverter;
+import org.springframework.data.mapping.model.EntityInstantiators;
 import org.springframework.data.redis.core.mapping.RedisMappingContext;
 import org.springframework.data.redis.core.mapping.RedisPersistentEntity;
 import org.springframework.data.redis.core.mapping.RedisPersistentProperty;
@@ -40,4 +41,10 @@ public interface RedisConverter
 	 */
 	@Nullable
 	IndexResolver getIndexResolver();
+
+	/**
+	 * @return the configured {@link EntityInstantiators}.
+	 * @since 3.2.4
+	 */
+	EntityInstantiators getEntityInstantiators();
 }

src/main/java/org/springframework/data/redis/repository/configuration/EnableRedisRepositories.java

@@ -33,6 +33,7 @@
 import org.springframework.data.redis.core.convert.KeyspaceConfiguration;
 import org.springframework.data.redis.core.index.IndexConfiguration;
 import org.springframework.data.redis.listener.KeyExpirationEventMessageListener;
+import org.springframework.data.redis.repository.query.RedisPartTreeQuery;
 import org.springframework.data.redis.repository.query.RedisQueryCreator;
 import org.springframework.data.redis.repository.support.RedisRepositoryFactoryBean;
 import org.springframework.data.repository.config.DefaultRepositoryBaseClass;
@@ -52,7 +53,7 @@
 @Documented
 @Inherited
 @Import(RedisRepositoriesRegistrar.class)
-@QueryCreatorType(RedisQueryCreator.class)
+@QueryCreatorType(value = RedisQueryCreator.class, repositoryQueryType = RedisPartTreeQuery.class)
 public @interface EnableRedisRepositories {
 
 	/**

src/main/java/org/springframework/data/redis/repository/query/RedisPartTreeQuery.java

@@ -0,0 +1,151 @@
+/*
+ * Copyright 2024 the original author or authors.
+ *
+ * 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
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License 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 org.springframework.data.redis.repository.query;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.data.convert.DtoInstantiatingConverter;
+import org.springframework.data.keyvalue.core.KeyValueOperations;
+import org.springframework.data.keyvalue.core.query.KeyValueQuery;
+import org.springframework.data.keyvalue.repository.query.KeyValuePartTreeQuery;
+import org.springframework.data.mapping.PersistentEntity;
+import org.springframework.data.mapping.PersistentProperty;
+import org.springframework.data.mapping.context.MappingContext;
+import org.springframework.data.mapping.model.EntityInstantiators;
+import org.springframework.data.redis.core.RedisKeyValueAdapter;
+import org.springframework.data.redis.core.convert.RedisConverter;
+import org.springframework.data.repository.query.ParameterAccessor;
+import org.springframework.data.repository.query.ParametersParameterAccessor;
+import org.springframework.data.repository.query.QueryMethod;
+import org.springframework.data.repository.query.QueryMethodEvaluationContextProvider;
+import org.springframework.data.repository.query.ResultProcessor;
+import org.springframework.data.repository.query.ReturnedType;
+import org.springframework.data.repository.query.parser.AbstractQueryCreator;
+import org.springframework.data.util.ReflectionUtils;
+import org.springframework.data.util.Streamable;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+
+/**
+ * Redis-specific implementation of {@link KeyValuePartTreeQuery} supporting projections.
+ *
+ * @author Mark Paluch
+ * @since 3.2.4
+ */
+public class RedisPartTreeQuery extends KeyValuePartTreeQuery {
+
+	private final RedisKeyValueAdapter adapter;
+
+	public RedisPartTreeQuery(QueryMethod queryMethod, QueryMethodEvaluationContextProvider evaluationContextProvider,
+			KeyValueOperations template, Class<? extends AbstractQueryCreator<?, ?>> queryCreator) {
+		super(queryMethod, evaluationContextProvider, template, queryCreator);
+		this.adapter = (RedisKeyValueAdapter) template.getKeyValueAdapter();
+	}
+
+	@Override
+	public Object execute(Object[] parameters) {
+
+		ParameterAccessor accessor = new ParametersParameterAccessor(getQueryMethod().getParameters(), parameters);
+		KeyValueQuery<?> query = prepareQuery(parameters);
+		ResultProcessor processor = getQueryMethod().getResultProcessor().withDynamicProjection(accessor);
+
+		RedisConverter converter = adapter.getConverter();
+		Converter<Object, Object> resultPostProcessor = new ResultProcessingConverter(processor,
+				converter.getMappingContext(), converter.getEntityInstantiators());
+
+		Object source = doExecute(parameters, query);
+		return source != null ? processor.processResult(resultPostProcessor.convert(source)) : null;
+	}
+
+	/**
+	 * A {@link Converter} to post-process all source objects using the given {@link ResultProcessor}.
+	 *
+	 * @author Mark Paluch
+	 */
+	static final class ResultProcessingConverter implements Converter<Object, Object> {
+
+		private final ResultProcessor processor;
+		private final MappingContext<? extends PersistentEntity<?, ?>, ? extends PersistentProperty<?>> context;
+		private final EntityInstantiators instantiators;
+
+		public ResultProcessingConverter(ResultProcessor processor,
+				MappingContext<? extends PersistentEntity<?, ?>, ? extends PersistentProperty<?>> context,
+				EntityInstantiators instantiators) {
+
+			Assert.notNull(processor, "Processor must not be null!");
+			Assert.notNull(context, "MappingContext must not be null!");
+			Assert.notNull(instantiators, "Instantiators must not be null!");
+
+			this.processor = processor;
+			this.context = context;
+			this.instantiators = instantiators;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
+		 */
+		@Override
+		public Object convert(Object source) {
+
+			if (source instanceof Set<?> s) {
+
+				Set<Object> target = new LinkedHashSet<>(s.size());
+
+				for (Object o : s) {
+					target.add(convert(o));
+				}
+
+				return target;
+			}
+
+			if (source instanceof Collection<?> c) {
+
+				List<Object> target = new ArrayList<>(c.size());
+
+				for (Object o : c) {
+					target.add(convert(o));
+				}
+
+				return target;
+			}
+
+			if (source instanceof Streamable<?> s) {
+				return s.map(this::convert);
+			}
+
+			ReturnedType returnedType = processor.getReturnedType();
+
+			if (ReflectionUtils.isVoid(returnedType.getReturnedType())) {
+				return null;
+			}
+
+			if (ClassUtils.isPrimitiveOrWrapper(returnedType.getReturnedType())) {
+				return source;
+			}
+
+			Converter<Object, Object> converter = new DtoInstantiatingConverter(returnedType.getReturnedType(), context,
+					instantiators);
+
+			return processor.processResult(source, converter);
+		}
+	}
+}

src/main/java/org/springframework/data/redis/repository/support/RedisRepositoryFactory.java

@@ -16,11 +16,11 @@
 package org.springframework.data.redis.repository.support;
 
 import org.springframework.data.keyvalue.core.KeyValueOperations;
-import org.springframework.data.keyvalue.repository.query.KeyValuePartTreeQuery;
 import org.springframework.data.keyvalue.repository.support.KeyValueRepositoryFactory;
 import org.springframework.data.redis.core.mapping.RedisMappingContext;
 import org.springframework.data.redis.core.mapping.RedisPersistentEntity;
 import org.springframework.data.redis.repository.core.MappingRedisEntityInformation;
+import org.springframework.data.redis.repository.query.RedisPartTreeQuery;
 import org.springframework.data.redis.repository.query.RedisQueryCreator;
 import org.springframework.data.repository.core.EntityInformation;
 import org.springframework.data.repository.core.RepositoryMetadata;
@@ -59,7 +59,7 @@ public RedisRepositoryFactory(KeyValueOperations keyValueOperations) {
 	 */
 	public RedisRepositoryFactory(KeyValueOperations keyValueOperations,
 			Class<? extends AbstractQueryCreator<?, ?>> queryCreator) {
-		this(keyValueOperations, queryCreator, KeyValuePartTreeQuery.class);
+		this(keyValueOperations, queryCreator, RedisPartTreeQuery.class);
 	}
 
 	/**

src/main/java/org/springframework/data/redis/repository/support/RedisRepositoryFactoryBean.java

@@ -18,6 +18,7 @@
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.data.keyvalue.core.KeyValueOperations;
 import org.springframework.data.keyvalue.repository.support.KeyValueRepositoryFactoryBean;
+import org.springframework.data.redis.repository.query.RedisPartTreeQuery;
 import org.springframework.data.repository.Repository;
 import org.springframework.data.repository.query.RepositoryQuery;
 import org.springframework.data.repository.query.parser.AbstractQueryCreator;
@@ -44,6 +45,7 @@ public class RedisRepositoryFactoryBean<T extends Repository<S, ID>, S, ID>
 	 */
 	public RedisRepositoryFactoryBean(Class<? extends T> repositoryInterface) {
 		super(repositoryInterface);
+		setQueryType(RedisPartTreeQuery.class);
 	}
 
 	@Override

src/test/java/org/springframework/data/redis/repository/RedisRepositoryIntegrationTestBase.java

@@ -51,6 +51,7 @@
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
 import org.springframework.data.repository.query.QueryByExampleExecutor;
+import org.springframework.data.util.Streamable;
 import org.springframework.lang.Nullable;
 
 /**
@@ -130,9 +131,13 @@ void shouldProjectSingleResult() {
 
 		repo.saveAll(Arrays.asList(rand, egwene));
 
-		PersonProjection projectionById = repo.findProjectionById(rand.getId());
-		assertThat(projectionById).isNotNull();
-		assertThat(projectionById.getFirstname()).isEqualTo(rand.firstname);
+		PersonProjection projection = repo.findProjectionById(rand.getId(), PersonProjection.class);
+		assertThat(projection).isNotNull();
+		assertThat(projection.getFirstname()).isEqualTo(rand.firstname);
+
+		PersonDto dto = repo.findProjectionById(rand.getId(), PersonDto.class);
+		assertThat(dto).isNotNull();
+		assertThat(dto.firstname()).isEqualTo(rand.firstname);
 	}
 
 	@Test // GH-2851
@@ -147,10 +152,20 @@ void shouldProjectCollection() {
 
 		repo.saveAll(Arrays.asList(rand, egwene));
 
-		List<PersonProjection> projectionById = repo.findProjectionBy();
-		assertThat(projectionById).hasSize(2) //
+		List<PersonProjection> projection = repo.findProjectionBy();
+		assertThat(projection).hasSize(2) //
 				.extracting(PersonProjection::getFirstname) //
 				.contains(rand.getFirstname(), egwene.getFirstname());
+
+		projection = repo.findProjectionStreamBy().toList();
+		assertThat(projection).hasSize(2) //
+				.extracting(PersonProjection::getFirstname) //
+				.contains(rand.getFirstname(), egwene.getFirstname());
+
+		List<PersonDto> dtos = repo.findProjectionDtoBy();
+		assertThat(dtos).hasSize(2) //
+				.extracting(PersonDto::firstname) //
+				.contains(rand.getFirstname(), egwene.getFirstname());
 	}
 
 	@Test // DATAREDIS-425
@@ -624,10 +639,14 @@ public interface PersonRepository extends PagingAndSortingRepository<Person, Str
 
 		Person findEntityById(String id);
 
-		PersonProjection findProjectionById(String id);
+		<T> T findProjectionById(String id, Class<T> projection);
+
+		Streamable<PersonProjection> findProjectionStreamBy();
 
 		List<PersonProjection> findProjectionBy();
 
+		List<PersonDto> findProjectionDtoBy();
+
 		@Override
 		<S extends Person> List<S> findAll(Example<S> example);
 	}
@@ -636,6 +655,9 @@ public interface PersonProjection {
 		String getFirstname();
 	}
 
+	record PersonDto(String firstname) {
+	}
+
 	public interface CityRepository extends CrudRepository<City, String> {
 
 		List<City> findByLocationNear(Point point, Distance distance);