DATAREDIS-605 - Polishing

Some minor code and documentation changes. More interestingly obtain the RedisConverter instead of the KeyValueAdapter for IndexResolver resolution in  QueryByExampleRedisExecutor and stick to findOne contract by throwing IncorrectResultSizeDataAccessException for queries returning non unique results.

Original Pull Request: #301

Author: christophstrobl

src/main/asciidoc/new-features.adoc

@@ -8,7 +8,7 @@ New and noteworthy in the latest releases.
 
 * Unix domain socket connections using <<redis:connectors:lettuce,Lettuce>>.
 * <<redis:write-to-master-read-from-slave, Write to Master read from Slave>> support using Lettuce.
-* <<query-by-example,Query by Example>> integration
+* <<query-by-example,Query by Example>> integration.
 
 [[new-in-2.0.0]]
 == New in Spring Data Redis 2.0

src/main/java/org/springframework/data/redis/core/RedisKeyValueTemplate.java

@@ -22,6 +22,7 @@
 import org.springframework.data.keyvalue.core.KeyValueAdapter;
 import org.springframework.data.keyvalue.core.KeyValueCallback;
 import org.springframework.data.keyvalue.core.KeyValueTemplate;
+import org.springframework.data.redis.core.convert.RedisConverter;
 import org.springframework.data.redis.core.mapping.RedisMappingContext;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -49,11 +50,13 @@ public RedisKeyValueTemplate(RedisKeyValueAdapter adapter, RedisMappingContext m
 	}
 
 	/**
-	 * @return the {@link RedisKeyValueAdapter}.
+	 * Obtain the underlying redis specific {@link org.springframework.data.convert.EntityConverter}.
+	 *
+	 * @return never {@literal null}.
 	 * @since 2.1
 	 */
-	public RedisKeyValueAdapter getAdapter() {
-		return adapter;
+	public RedisConverter getConverter() {
+		return adapter.getConverter();
 	}
 
 	/*
@@ -65,7 +68,6 @@ public RedisMappingContext getMappingContext() {
 		return (RedisMappingContext) super.getMappingContext();
 	}
 
-
 	/**
 	 * Retrieve entities by resolving their {@literal id}s and converting them into required type. <br />
 	 * The callback provides either a single {@literal id} or an {@link Iterable} of {@literal id}s, used for retrieving
@@ -104,15 +106,13 @@ public List<T> doInRedis(RedisKeyValueAdapter adapter) {
 				}
 
 				Iterable<?> ids = ClassUtils.isAssignable(Iterable.class, callbackResult.getClass())
-						? (Iterable<?>) callbackResult
-						: Collections.singleton(callbackResult);
+						? (Iterable<?>) callbackResult : Collections.singleton(callbackResult);
 
 				List<T> result = new ArrayList<>();
 				for (Object id : ids) {
 
 					String idToUse = adapter.getConverter().getConversionService().canConvert(id.getClass(), String.class)
-							? adapter.getConverter().getConversionService().convert(id, String.class)
-							: id.toString();
+							? adapter.getConverter().getConversionService().convert(id, String.class) : id.toString();
 
 					findById(idToUse, type).ifPresent(result::add);
 				}

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

@@ -20,6 +20,7 @@
 import java.util.List;
 import java.util.Optional;
 
+import org.springframework.dao.IncorrectResultSizeDataAccessException;
 import org.springframework.data.domain.Example;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageImpl;
@@ -29,7 +30,6 @@
 import org.springframework.data.redis.core.RedisKeyValueTemplate;
 import org.springframework.data.redis.core.convert.IndexResolver;
 import org.springframework.data.redis.core.convert.PathIndexResolver;
-import org.springframework.data.redis.core.convert.RedisConverter;
 import org.springframework.data.redis.repository.query.ExampleQueryMapper;
 import org.springframework.data.redis.repository.query.RedisOperationChain;
 import org.springframework.data.repository.core.EntityInformation;
@@ -43,6 +43,7 @@
  * methods.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  * @since 2.1
  */
 @SuppressWarnings("unchecked")
@@ -62,17 +63,9 @@ public class QueryByExampleRedisExecutor<T> implements QueryByExampleExecutor<T>
 	public QueryByExampleRedisExecutor(EntityInformation<T, ?> entityInformation,
 			RedisKeyValueTemplate keyValueTemplate) {
 
-		Assert.notNull(entityInformation, "EntityInformation must not be null!");
-		Assert.notNull(keyValueTemplate, "RedisKeyValueTemplate must not be null!");
-
-		this.entityInformation = entityInformation;
-		this.keyValueTemplate = keyValueTemplate;
-
-		RedisConverter converter = keyValueTemplate.getAdapter().getConverter();
-		IndexResolver indexResolver = converter.getIndexResolver();
-
-		this.mapper = new ExampleQueryMapper(keyValueTemplate.getMappingContext(),
-				indexResolver != null ? indexResolver : new PathIndexResolver(converter.getMappingContext()));
+		this(entityInformation, keyValueTemplate,
+				keyValueTemplate.getConverter().getIndexResolver() != null ? keyValueTemplate.getConverter().getIndexResolver()
+						: new PathIndexResolver(keyValueTemplate.getMappingContext()));
 	}
 
 	/**
@@ -91,8 +84,7 @@ public QueryByExampleRedisExecutor(EntityInformation<T, ?> entityInformation, Re
 		this.entityInformation = entityInformation;
 		this.keyValueTemplate = keyValueTemplate;
 
-		this.mapper = new ExampleQueryMapper(keyValueTemplate.getMappingContext(),
-				new PathIndexResolver(keyValueTemplate.getMappingContext()));
+		this.mapper = new ExampleQueryMapper(keyValueTemplate.getMappingContext(), indexResolver);
 	}
 
 	/*
@@ -102,13 +94,21 @@ public QueryByExampleRedisExecutor(EntityInformation<T, ?> entityInformation, Re
 	@Override
 	public <S extends T> Optional<S> findOne(Example<S> example) {
 
-		RedisOperationChain operationChain = getQuery(example);
+		RedisOperationChain operationChain = createQuery(example);
 
 		KeyValueQuery<RedisOperationChain> query = new KeyValueQuery<>(operationChain);
-		Iterable<T> result = keyValueTemplate.find(query.limit(1), entityInformation.getJavaType());
-		Iterator<T> iterator = result.iterator();
+		Iterator<T> iterator = keyValueTemplate.find(query.limit(2), entityInformation.getJavaType()).iterator();
+
+		Optional result = Optional.empty();
+
+		if (iterator.hasNext()) {
+			result = Optional.of((S) iterator.next());
+			if (iterator.hasNext()) {
+				throw new IncorrectResultSizeDataAccessException(1);
+			}
+		}
 
-		return iterator.hasNext() ? Optional.of((S) iterator.next()) : Optional.empty();
+		return result;
 	}
 
 	/*
@@ -118,7 +118,7 @@ public <S extends T> Optional<S> findOne(Example<S> example) {
 	@Override
 	public <S extends T> Iterable<S> findAll(Example<S> example) {
 
-		RedisOperationChain operationChain = getQuery(example);
+		RedisOperationChain operationChain = createQuery(example);
 
 		return (Iterable<S>) keyValueTemplate.find(new KeyValueQuery<>(operationChain), entityInformation.getJavaType());
 	}
@@ -141,7 +141,7 @@ public <S extends T> Page<S> findAll(Example<S> example, Pageable pageable) {
 
 		Assert.notNull(pageable, "Pageable must not be null!");
 
-		RedisOperationChain operationChain = getQuery(example);
+		RedisOperationChain operationChain = createQuery(example);
 
 		KeyValueQuery<RedisOperationChain> query = new KeyValueQuery<>(operationChain);
 		Iterable<T> result = keyValueTemplate.find(
@@ -166,7 +166,7 @@ public <S extends T> Page<S> findAll(Example<S> example, Pageable pageable) {
 	@Override
 	public <S extends T> long count(Example<S> example) {
 
-		RedisOperationChain operationChain = getQuery(example);
+		RedisOperationChain operationChain = createQuery(example);
 
 		return keyValueTemplate.count(new KeyValueQuery<>(operationChain), entityInformation.getJavaType());
 	}
@@ -180,7 +180,7 @@ public <S extends T> boolean exists(Example<S> example) {
 		return count(example) > 0;
 	}
 
-	private <S extends T> RedisOperationChain getQuery(Example<S> example) {
+	private <S extends T> RedisOperationChain createQuery(Example<S> example) {
 
 		Assert.notNull(example, "Example must not be null!");
 

src/test/java/org/springframework/data/redis/repository/query/ExampleQueryMapperUnitTests.java

@@ -40,6 +40,7 @@
  * Unit tests for {@link ExampleQueryMapper}.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  */
 public class ExampleQueryMapperUnitTests {
 
@@ -186,7 +187,7 @@ public void shouldApplyPropertyTransformation() {
 	}
 
 	@Data
-	public static class Person {
+	static class Person {
 
 		@Id String id;
 
@@ -204,7 +205,8 @@ public static class Person {
 		Species species;
 	}
 
-	public enum Gender {
+	enum Gender {
+
 		MALE, FEMALE {
 
 			@Override
@@ -214,7 +216,7 @@ public String toString() {
 		}
 	}
 
-	public static class Species {
+	static class Species {
 
 		@Indexed String name;
 	}

src/test/java/org/springframework/data/redis/repository/support/QueryByExampleRedisExecutorTests.java

@@ -27,6 +27,7 @@
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
+import org.springframework.dao.IncorrectResultSizeDataAccessException;
 import org.springframework.data.annotation.Id;
 import org.springframework.data.domain.Example;
 import org.springframework.data.domain.Page;
@@ -48,6 +49,7 @@
  * Integration tests for {@link QueryByExampleRedisExecutor}.
  *
  * @author Mark Paluch
+ * @author Christoph Strobl
  */
 public class QueryByExampleRedisExecutorTests {
 
@@ -101,6 +103,19 @@ public void shouldFindOneByExample() {
 		assertThat(result).contains(walt);
 	}
 
+	@Test // DATAREDIS-605
+	public void shouldThrowExceptionWhenFindOneByExampleReturnsNonUniqueResult() {
+
+		QueryByExampleRedisExecutor<Person> executor = new QueryByExampleRedisExecutor<>(getEntityInformation(Person.class),
+				kvTemplate);
+
+		Person person = new Person();
+		person.setHometown(walt.getHometown());
+
+		assertThatThrownBy(() -> executor.findOne(Example.of(person)))
+				.isInstanceOf(IncorrectResultSizeDataAccessException.class);
+	}
+
 	@Test // DATAREDIS-605
 	public void shouldNotFindOneByExample() {