Fall back to canonical constructor in constructor resolution when using Java Records.

We now fall back to the canonical constructor of records when we cannot disambiguate which constructor to use.

Also, reflect the Kotlin persistence creator mechanism.

Closes #2625
Original pull request: #2694.

Author: mp911de

src/main/asciidoc/object-mapping.adoc

@@ -20,7 +20,8 @@ The resolution algorithm works as follows:
 1. If there is a single static factory method annotated with `@PersistenceCreator` then it is used.
 2. If there is a single constructor, it is used.
 3. If there are multiple constructors and exactly one is annotated with `@PersistenceCreator`, it is used.
-4. If there's a no-argument constructor, it is used.
+4. If the type is a Java `Record` the canonical constructor is used.
+5. If there's a no-argument constructor, it is used.
 Other constructors will be ignored.
 
 The value resolution assumes constructor/factory method argument names to match the property names of the entity, i.e. the resolution will be performed as if the property was to be populated, including all customizations in mapping (different datastore column or field name etc.).
@@ -295,9 +296,23 @@ Using the same field/column name for different values typically leads to corrupt
 
 Spring Data adapts specifics of Kotlin to allow object creation and mutation.
 
+[[mapping.kotlin.creation]]
 === Kotlin object creation
 
-Kotlin classes are supported to be instantiated , all classes are immutable by default and require explicit property declarations to define mutable properties.
+Kotlin classes are supported to be instantiated, all classes are immutable by default and require explicit property declarations to define mutable properties.
+
+Spring Data automatically tries to detect a persistent entity's constructor to be used to materialize objects of that type.
+The resolution algorithm works as follows:
+
+1. If there is a constructor that is annotated with `@PersistenceCreator`, it is used.
+2. If the type is a <<mapping.kotlin,Kotlin data cass>> the primary constructor is used.
+3. If there is a single static factory method annotated with `@PersistenceCreator` then it is used.
+4. If there is a single constructor, it is used.
+5. If there are multiple constructors and exactly one is annotated with `@PersistenceCreator`, it is used.
+6. If the type is a Java `Record` the canonical constructor is used.
+7. If there's a no-argument constructor, it is used.
+Other constructors will be ignored.
+
 Consider the following `data` class `Person`:
 
 ====

src/main/java/org/springframework/data/mapping/model/InstantiationAwarePropertyAccessor.java

@@ -18,7 +18,6 @@
 import java.util.function.Function;
 
 import org.springframework.core.KotlinDetector;
-import org.springframework.data.annotation.PersistenceConstructor;
 import org.springframework.data.mapping.InstanceCreatorMetadata;
 import org.springframework.data.mapping.Parameter;
 import org.springframework.data.mapping.PersistentEntity;
@@ -28,9 +27,10 @@
 import org.springframework.util.Assert;
 
 /**
- * A {@link PersistentPropertyAccessor} that will use an entity's {@link PersistenceConstructor} to create a new
- * instance of it to apply a new value for a given {@link PersistentProperty}. Will only be used if the
- * {@link PersistentProperty} is to be applied on a completely immutable entity type exposing a persistence constructor.
+ * A {@link PersistentPropertyAccessor} that will use an entity's
+ * {@link org.springframework.data.annotation.PersistenceCreator} to create a new instance of it to apply a new value
+ * for a given {@link PersistentProperty}. Will only be used if the {@link PersistentProperty} is to be applied on a
+ * completely immutable entity type exposing a entity creator.
  *
  * @author Oliver Drotbohm
  * @author Mark Paluch
@@ -91,8 +91,7 @@ public void setProperty(PersistentProperty<?> property, @Nullable Object value)
 		}
 
 		if (!creator.isCreatorParameter(property)) {
-			throw new IllegalStateException(
-					String.format(NO_CONSTRUCTOR_PARAMETER, property.getName(), creator));
+			throw new IllegalStateException(String.format(NO_CONSTRUCTOR_PARAMETER, property.getName(), creator));
 		}
 
 		creator.getParameters().forEach(it -> {

src/main/java/org/springframework/data/mapping/model/PreferredConstructorDiscoverer.java

@@ -22,6 +22,7 @@
 
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Constructor;
+import java.lang.reflect.RecordComponent;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -34,11 +35,11 @@
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.PreferredConstructor;
-import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.data.util.KotlinReflectionUtils;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 
 /**
  * Helper class to find a {@link PreferredConstructor}.
@@ -49,7 +50,7 @@
  * @author Mark Paluch
  * @author Xeno Amess
  */
-public interface PreferredConstructorDiscoverer<T, P extends PersistentProperty<P>> {
+public interface PreferredConstructorDiscoverer {
 
 	/**
 	 * Discovers the {@link PreferredConstructor} for the given type.
@@ -124,12 +125,45 @@ <T, P extends PersistentProperty<P>> PreferredConstructor<T, P> discover(TypeInf
 					}
 				}
 
+				if (rawOwningType.isRecord() && (candidates.size() > 1 || (noArg != null && !candidates.isEmpty()))) {
+					return RECORD.discover(type, entity);
+				}
+
 				if (noArg != null) {
 					return buildPreferredConstructor(noArg, type, entity);
 				}
 
-				return candidates.size() > 1 || candidates.isEmpty() ? null
-						: buildPreferredConstructor(candidates.iterator().next(), type, entity);
+				if (candidates.size() == 1) {
+					return buildPreferredConstructor(candidates.iterator().next(), type, entity);
+				}
+
+				return null;
+			}
+		},
+
+		/**
+		 * Discovers the canonical constructor for Java Record types.
+		 *
+		 * @since 3.0
+		 */
+		RECORD {
+
+			@Nullable
+			@Override
+			<T, P extends PersistentProperty<P>> PreferredConstructor<T, P> discover(TypeInformation<T> type,
+					@Nullable PersistentEntity<T, P> entity) {
+
+				Class<?> rawOwningType = type.getType();
+
+				if (!rawOwningType.isRecord()) {
+					return null;
+				}
+
+				Class<?>[] paramTypes = Arrays.stream(rawOwningType.getRecordComponents()).map(RecordComponent::getType)
+						.toArray(Class<?>[]::new);
+				Constructor<?> canonicalConstructor = ClassUtils.getConstructorIfAvailable(rawOwningType, paramTypes);
+
+				return canonicalConstructor != null ? buildPreferredConstructor(canonicalConstructor, type, entity) : null;
 			}
 		},
 

src/test/java/org/springframework/data/mapping/InstantiationAwarePersistentPropertyAccessorUnitTests.java

@@ -20,6 +20,7 @@
 import lombok.Value;
 
 import org.junit.jupiter.api.Test;
+
 import org.springframework.data.mapping.context.SampleMappingContext;
 import org.springframework.data.mapping.context.SamplePersistentProperty;
 import org.springframework.data.mapping.model.EntityInstantiators;
@@ -44,8 +45,7 @@ void shouldCreateNewInstance() {
 		var sample = new Sample("Dave", "Matthews", 42);
 
 		PersistentPropertyAccessor<Sample> wrapper = new InstantiationAwarePropertyAccessor<>(sample,
-				entity::getPropertyAccessor,
-				instantiators);
+				entity::getPropertyAccessor, instantiators);
 
 		wrapper.setProperty(entity.getRequiredPersistentProperty("firstname"), "Oliver August");
 
@@ -71,10 +71,38 @@ void shouldSetMultipleProperties() {
 		assertThat(wrapper.getBean()).isEqualTo(new Sample("Oliver August", "Heisenberg", 42));
 	}
 
+	@Test // GH-2625
+	void shouldSetPropertyOfRecordUsingCanonicalConstructor() {
+
+		var instantiators = new EntityInstantiators();
+		var context = new SampleMappingContext();
+
+		PersistentEntity<Object, SamplePersistentProperty> entity = context
+				.getRequiredPersistentEntity(WithSingleArgConstructor.class);
+
+		var bean = new WithSingleArgConstructor(42L, "Dave");
+
+		PersistentPropertyAccessor<WithSingleArgConstructor> wrapper = new InstantiationAwarePropertyAccessor<>(bean,
+				entity::getPropertyAccessor, instantiators);
+
+		wrapper.setProperty(entity.getRequiredPersistentProperty("name"), "Oliver August");
+		wrapper.setProperty(entity.getRequiredPersistentProperty("id"), 41L);
+
+		assertThat(wrapper.getBean()).isEqualTo(new WithSingleArgConstructor(41L, "Oliver August"));
+	}
+
 	@Value
 	static class Sample {
 
 		String firstname, lastname;
 		int age;
 	}
+
+	public record WithSingleArgConstructor(Long id, String name) {
+
+		public WithSingleArgConstructor(String name) {
+			this(null, name);
+		}
+	}
+
 }

src/test/java/org/springframework/data/mapping/PreferredConstructorDiscovererUnitTests.java

@@ -26,6 +26,7 @@
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.data.annotation.PersistenceConstructor;
+import org.springframework.data.annotation.PersistenceCreator;
 import org.springframework.data.mapping.PreferredConstructorDiscovererUnitTests.Outer.Inner;
 import org.springframework.data.mapping.model.BasicPersistentEntity;
 import org.springframework.data.mapping.model.PreferredConstructorDiscoverer;
@@ -149,6 +150,34 @@ void detectsMetaAnnotatedValueAnnotation() {
 		});
 	}
 
+	@Test // GH-2332
+	void detectsCanonicalRecordConstructor() {
+
+		assertThat(PreferredConstructorDiscoverer.discover(RecordWithSingleArgConstructor.class)).satisfies(ctor -> {
+
+			assertThat(ctor.getParameters()).hasSize(2);
+			assertThat(ctor.getParameters().get(0).getRawType()).isEqualTo(Long.class);
+			assertThat(ctor.getParameters().get(1).getRawType()).isEqualTo(String.class);
+		});
+
+		assertThat(PreferredConstructorDiscoverer.discover(RecordWithNoArgConstructor.class)).satisfies(ctor -> {
+
+			assertThat(ctor.getParameters()).hasSize(2);
+			assertThat(ctor.getParameters().get(0).getRawType()).isEqualTo(Long.class);
+			assertThat(ctor.getParameters().get(1).getRawType()).isEqualTo(String.class);
+		});
+	}
+
+	@Test // GH-2332
+	void detectsAnnotatedRecordConstructor() {
+
+		assertThat(PreferredConstructorDiscoverer.discover(RecordWithPersistenceCreator.class)).satisfies(ctor -> {
+
+			assertThat(ctor.getParameters()).hasSize(1);
+			assertThat(ctor.getParameters().get(0).getRawType()).isEqualTo(String.class);
+		});
+	}
+
 	static class SyntheticConstructor {
 		@PersistenceConstructor
 		private SyntheticConstructor(String x) {}
@@ -227,5 +256,28 @@ static class ClassWithMetaAnnotatedParameter {
 	@Target(ElementType.PARAMETER)
 	@Retention(RetentionPolicy.RUNTIME)
 	@Value("${hello-world}")
-	@interface MyValue {}
+	@interface MyValue {
+	}
+
+	public record RecordWithSingleArgConstructor(Long id, String name) {
+
+		public RecordWithSingleArgConstructor(String name) {
+			this(null, name);
+		}
+	}
+
+	public record RecordWithNoArgConstructor(Long id, String name) {
+
+		public RecordWithNoArgConstructor(String name) {
+			this(null, null);
+		}
+	}
+
+	public record RecordWithPersistenceCreator(Long id, String name) {
+
+		@PersistenceCreator
+		public RecordWithPersistenceCreator(String name) {
+			this(null, name);
+		}
+	}
 }