Guard potential NPE in TupleConverter.

Also fix a broken reference in javadoc.

Original Pull Request: #3654

Author: christophstrobl

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

@@ -23,6 +23,7 @@
 import jakarta.persistence.TupleElement;
 import jakarta.persistence.TypedQuery;
 
+import java.lang.reflect.Constructor;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
@@ -54,6 +55,7 @@
 import org.springframework.jdbc.support.JdbcUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -345,7 +347,7 @@ public TupleConverter(ReturnedType type, boolean nativeQuery) {
 					&& !type.getInputProperties().isEmpty();
 
 			if (this.dtoProjection) {
-				this.preferredConstructor = PreferredConstructorDiscoverer.discover(String.class);
+				 this.preferredConstructor = PreferredConstructorDiscoverer.discover(type.getReturnedType());
 			} else {
 				this.preferredConstructor = null;
 			}
@@ -373,18 +375,35 @@ public Object convert(Object source) {
 
 				Object[] ctorArgs = new Object[type.getInputProperties().size()];
 
+				boolean containsNullValue = false;
 				for (int i = 0; i < type.getInputProperties().size(); i++) {
-					ctorArgs[i] = tuple.get(i);
+					Object value = tuple.get(i);
+					ctorArgs[i] = value;
+					if (!containsNullValue && value == null) {
+						containsNullValue = true;
+					}
 				}
 
 				try {
 
-					if (preferredConstructor.getParameterCount() == ctorArgs.length) {
+					if (preferredConstructor != null && preferredConstructor.getParameterCount() == ctorArgs.length) {
 						return BeanUtils.instantiateClass(preferredConstructor.getConstructor(), ctorArgs);
 					}
 
-					return BeanUtils.instantiateClass(type.getReturnedType()
-							.getConstructor(Arrays.stream(ctorArgs).map(Object::getClass).toArray(Class<?>[]::new)), ctorArgs);
+					Constructor<?> ctor = null;
+
+					if (!containsNullValue) { // let's seem if we have an argument type match
+						ctor = type.getReturnedType()
+								.getConstructor(Arrays.stream(ctorArgs).map(Object::getClass).toArray(Class<?>[]::new));
+					}
+
+					if (ctor == null) { // let's see if there's more general constructor we could use that accepts our args
+						ctor = findFirstMatchingConstructor(ctorArgs);
+					}
+
+					if (ctor != null) {
+						return BeanUtils.instantiateClass(ctor, ctorArgs);
+					}
 				} catch (ReflectiveOperationException e) {
 					ReflectionUtils.handleReflectionException(e);
 				}
@@ -393,6 +412,30 @@ public Object convert(Object source) {
 			return new TupleBackedMap(tupleWrapper.apply(tuple));
 		}
 
+		@Nullable
+		private Constructor<?> findFirstMatchingConstructor(Object[] ctorArgs) {
+
+			for (Constructor<?> ctor : type.getReturnedType().getDeclaredConstructors()) {
+
+				if (ctor.getParameterCount() == ctorArgs.length) {
+					boolean itsAMatch = true;
+					for (int i = 0; i < ctor.getParameterCount(); i++) {
+						if (ctorArgs[i] == null) {
+							continue;
+						}
+						if (!ClassUtils.isAssignable(ctor.getParameterTypes()[i], ctorArgs[i].getClass())) {
+							itsAMatch = false;
+							break;
+						}
+					}
+					if (itsAMatch) {
+						return ctor;
+					}
+				}
+			}
+			return null;
+		}
+
 		/**
 		 * A {@link Map} implementation which delegates all calls to a {@link Tuple}. Depending on the provided
 		 * {@link Tuple} implementation it might return the same value for various keys of which only one will appear in the

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

@@ -82,7 +82,7 @@ public interface QueryEnhancer {
 	 * @param sort the sort specification to apply.
 	 * @param alias the alias to be used in the order by clause. May be {@literal null} or empty.
 	 * @return the modified query string.
-	 * @deprecated since 3.5, use {@link #rewrite(Sort, ReturnedType)} instead.
+	 * @deprecated since 3.5, use {@link #rewrite(QueryRewriteInformation)} instead.
 	 */
 	@Deprecated(since = "3.5", forRemoval = true)
 	String applySorting(Sort sort, @Nullable String alias);

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

@@ -37,6 +37,7 @@
 
 import org.springframework.data.jpa.repository.query.AbstractJpaQuery.TupleConverter;
 import org.springframework.data.projection.ProjectionFactory;
+import org.springframework.data.projection.SpelAwareProxyProjectionFactory;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.core.RepositoryMetadata;
 import org.springframework.data.repository.core.support.DefaultRepositoryMetadata;
@@ -113,6 +114,16 @@ void findsValuesForAllVariantsSupportedByTheTuple() {
 		softly.assertAll();
 	}
 
+	@Test // GH-3076
+	void dealsWithNullsInArgumetents() {
+
+		ReturnedType returnedType = ReturnedType.of(WithPC.class, DomainType.class, new SpelAwareProxyProjectionFactory());
+
+		when(tuple.get(eq(0))).thenReturn("one");
+		when(tuple.get(eq(1))).thenReturn(null);
+		new TupleConverter(returnedType).convert(tuple);
+	}
+
 	interface SampleRepository extends CrudRepository<Object, Long> {
 		String someMethod();
 	}
@@ -177,4 +188,18 @@ public String getAlias() {
 			}
 		}
 	}
+
+	static class DomainType {
+		String one, two, three;
+	}
+
+	static class  WithPC {
+		String one;
+		String two;
+
+		public WithPC(String one, String two) {
+			this.one = one;
+			this.two = two;
+		}
+	}
 }

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

@@ -68,7 +68,7 @@ This query gets rewritten to `SELECT new UserDto(u.firstname, u.lastname) FROM U
 
 [WARNING]
 ====
-JPQL constructor expressions must not contain aliases for selected columns.
+JPQL constructor expressions must not contain aliases for selected columns and query rewriting will not remove them for you.
 While `SELECT u as user, count(u.roles) as roleCount FROM USER u …` is a valid query for interface-based projections that rely on column names from the returned `Tuple`, the same construct is invalid when requesting a DTO where it needs to be `SELECT u, count(u.roles) FROM USER u …`. +
 Some persistence providers may be lenient about this, others not.
 ====