Add camelCase to snake_case fallback for native query projections.

Closes #3462
Original pull request: #3472

Author: quaff

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/AbstractJpaQuery.java

@@ -47,6 +47,7 @@
 import org.springframework.data.repository.query.ResultProcessor;
 import org.springframework.data.repository.query.ReturnedType;
 import org.springframework.data.util.Lazy;
+import org.springframework.jdbc.support.JdbcUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
@@ -62,6 +63,7 @@
  * @author Сергей Цыпанов
  * @author Wonchul Heo
  * @author Julia Lee
+ * @author Yanming Zhou
  */
 public abstract class AbstractJpaQuery implements RepositoryQuery {
 
@@ -149,7 +151,7 @@ private Object doExecute(JpaQueryExecution execution, Object[] values) {
 		Object result = execution.execute(this, accessor);
 
 		ResultProcessor withDynamicProjection = method.getResultProcessor().withDynamicProjection(accessor);
-		return withDynamicProjection.processResult(result, new TupleConverter(withDynamicProjection.getReturnedType()));
+		return withDynamicProjection.processResult(result, new TupleConverter(withDynamicProjection.getReturnedType(), method.isNativeQuery()));
 	}
 
 	private JpaParametersParameterAccessor obtainParameterAccessor(Object[] values) {
@@ -304,16 +306,30 @@ static class TupleConverter implements Converter<Object, Object> {
 
 		private final ReturnedType type;
 
+		private final boolean nativeQuery;
+
 		/**
 		 * Creates a new {@link TupleConverter} for the given {@link ReturnedType}.
 		 *
 		 * @param type must not be {@literal null}.
 		 */
 		public TupleConverter(ReturnedType type) {
 
+			this(type, false);
+		}
+
+		/**
+		 * Creates a new {@link TupleConverter} for the given {@link ReturnedType}.
+		 *
+		 * @param type must not be {@literal null}.
+		 * @param nativeQuery is this converter for native query?
+		 */
+		public TupleConverter(ReturnedType type, boolean nativeQuery) {
+
 			Assert.notNull(type, "Returned type must not be null");
 
 			this.type = type;
+			this.nativeQuery = nativeQuery;
 		}
 
 		@Override
@@ -334,7 +350,7 @@ public Object convert(Object source) {
 				}
 			}
 
-			return new TupleBackedMap(tuple);
+			return new TupleBackedMap(nativeQuery ? new NativeTupleWrapper(tuple) : tuple);
 		}
 
 		/**
@@ -451,4 +467,76 @@ public Set<Entry<String, Object>> entrySet() {
 			}
 		}
 	}
+
+	private static class NativeTupleWrapper implements Tuple {
+
+		private final Tuple underlying;
+
+		NativeTupleWrapper(Tuple underlying) {
+			this.underlying = underlying;
+		}
+
+		String fallback(String alias) {
+			return JdbcUtils.convertPropertyNameToUnderscoreName(alias);
+		}
+
+		@Override
+		public <X> X get(TupleElement<X> tupleElement) {
+			try {
+				return underlying.get(tupleElement);
+			} catch (IllegalArgumentException original) {
+				try {
+					return underlying.get(fallback(tupleElement.getAlias()), tupleElement.getJavaType());
+				} catch (IllegalArgumentException ignored) {
+					throw original;
+				}
+			}
+		}
+
+		@Override
+		public <X> X get(String s, Class<X> aClass) {
+			try {
+				return underlying.get(s, aClass);
+			} catch (IllegalArgumentException original) {
+				try {
+					return underlying.get(fallback(s), aClass);
+				} catch (IllegalArgumentException ignored) {
+					throw original;
+				}
+			}
+		}
+
+		@Override
+		public Object get(String s) {
+			try {
+				return underlying.get(s);
+			} catch (IllegalArgumentException original) {
+				try {
+					return underlying.get(fallback(s));
+				} catch (IllegalArgumentException ignored) {
+					throw original;
+				}
+			}
+		}
+
+		@Override
+		public <X> X get(int i, Class<X> aClass) {
+			return underlying.get(i, aClass);
+		}
+
+		@Override
+		public Object get(int i) {
+			return underlying.get(i);
+		}
+
+		@Override
+		public Object[] toArray() {
+			return underlying.toArray();
+		}
+
+		@Override
+		public List<TupleElement<?>> getElements() {
+			return underlying.getElements();
+		}
+	}
 }

spring-data-jpa/src/test/java/org/springframework/data/jpa/domain/sample/User.java

@@ -33,6 +33,7 @@
  * @author Jeff Sheets
  * @author JyotirmoyVS
  * @author Greg Turnquist
+ * @author Yanming Zhou
  */
 @Entity
 @NamedEntityGraphs({ @NamedEntityGraph(name = "User.overview", attributeNodes = { @NamedAttributeNode("roles") }),
@@ -101,6 +102,8 @@ public class User {
 
 	@Column(nullable = false, unique = true) private String emailAddress;
 
+	@Column(name = "secondary_email_address") private String secondaryEmailAddress;
+
 	@ManyToMany(cascade = { CascadeType.PERSIST, CascadeType.MERGE }) private Set<User> colleagues;
 
 	@ManyToMany private Set<Role> roles;
@@ -173,6 +176,14 @@ public void setEmailAddress(String emailAddress) {
 		this.emailAddress = emailAddress;
 	}
 
+	public String getSecondaryEmailAddress() {
+		return secondaryEmailAddress;
+	}
+
+	public void setSecondaryEmailAddress(String secondaryEmailAddress) {
+		this.secondaryEmailAddress = secondaryEmailAddress;
+	}
+
 	public void setActive(boolean active) {
 		this.active = active;
 	}

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java

@@ -95,6 +95,7 @@
  * @author Simon Paradies
  * @author Geoffrey Deremetz
  * @author Krzysztof Krason
+ * @author Yanming Zhou
  */
 @ExtendWith(SpringExtension.class)
 @ContextConfiguration("classpath:application-context.xml")
@@ -2970,6 +2971,24 @@ void supportsProjectionsWithNativeQueriesAndCamelCaseProperty() {
 				.isNotNull();
 	}
 
+	@Test // DATAJPA-3462
+	void supportsProjectionsWithNativeQueriesAndUnderscoresColumnNameToCamelCaseProperty() {
+
+		User user = new User();
+		user.setEmailAddress("primary@something");
+		user.setSecondaryEmailAddress("secondary@something");
+		em.persist(user);
+
+		UserRepository.EmailOnly result = repository.findEmailOnlyByNativeQuery(user.getId());
+
+		String secondaryEmailAddress = result.getSecondaryEmailAddress();
+
+		assertThat(secondaryEmailAddress) //
+				.isEqualTo(user.getSecondaryEmailAddress()) //
+				.as("ensuring secondary email is actually not null") //
+				.isNotNull();
+	}
+
 	@Test // DATAJPA-1235
 	void handlesColonsFollowedByIntegerInStringLiteral() {
 

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/sample/UserRepository.java

@@ -62,6 +62,7 @@
  * @author Simon Paradies
  * @author Diego Krupitza
  * @author Geoffrey Deremetz
+ * @author Yanming Zhou
  */
 public interface UserRepository extends JpaRepository<User, Integer>, JpaSpecificationExecutor<User>,
 		UserRepositoryCustom, ListQuerydslPredicateExecutor<User> {
@@ -555,7 +556,7 @@ List<User> findUsersByFirstnameForSpELExpressionWithParameterIndexOnlyWithEntity
 	NameOnly findByNativeQuery(Integer id);
 
 	// DATAJPA-1248
-	@Query(value = "SELECT emailaddress FROM SD_User WHERE id = ?1", nativeQuery = true)
+	@Query(value = "SELECT emailaddress, secondary_email_address FROM SD_User WHERE id = ?1", nativeQuery = true)
 	EmailOnly findEmailOnlyByNativeQuery(Integer id);
 
 	// DATAJPA-1235
@@ -721,6 +722,8 @@ interface NameOnly {
 
 	interface EmailOnly {
 		String getEmailAddress();
+
+		String getSecondaryEmailAddress();
 	}
 
 	interface IdOnly {