DATAJPA-633 - Back-ported detection of targetEntity attribute.

Back port of the fix for DATAJPA-664 to make sure interface types can be used for associations. This broke in the Dijkstra/Evans train due to the fix in DATACMNS-479 and now most recently pops up in the use of Maps with interfaces as values.

Related tickets: DATAJPA-664, DATACMNS-479.

src/main/java/org/springframework/data/jpa/mapping/JpaPersistentPropertyImpl.java

@@ -34,10 +34,13 @@ import javax.persistence.OneToOne;
 import javax.persistence.Transient;
 import javax.persistence.metamodel.Metamodel;
 
+import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.data.mapping.Association;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.model.AnnotationBasedPersistentProperty;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
+import org.springframework.data.util.ClassTypeInformation;
+import org.springframework.data.util.TypeInformation;
 import org.springframework.util.Assert;
 
 /**
@@ -46,8 +49,8 @@ import org.springframework.util.Assert;
  * @author Oliver Gierke
  * @since 1.3
  */
-class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPersistentProperty> implements
-		JpaPersistentProperty {
+class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPersistentProperty>
+		implements JpaPersistentProperty {
 
 	private static final Collection<Class<? extends Annotation>> ASSOCIATION_ANNOTATIONS;
 	private static final Collection<Class<? extends Annotation>> ID_ANNOTATIONS;
@@ -71,6 +74,7 @@ class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPer
 	}
 
 	private final Metamodel metamodel;
+	private final TypeInformation<?> associationTargetType;
 
 	/**
 	 * Creates a new {@link JpaPersistentPropertyImpl}
@@ -89,6 +93,26 @@ class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPer
 		Assert.notNull(metamodel, "Metamodel must not be null!");
 
 		this.metamodel = metamodel;
+		this.associationTargetType = isAssociation() ? detectAssociationTargetType() : null;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mapping.model.AbstractPersistentProperty#getActualType()
+	 */
+	@Override
+	public Class<?> getActualType() {
+		return associationTargetType == null ? super.getActualType() : associationTargetType.getType();
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mapping.model.AbstractPersistentProperty#getPersistentEntityType()
+	 */
+	@Override
+	public Iterable<? extends TypeInformation<?>> getPersistentEntityType() {
+		return associationTargetType == null ? super.getPersistentEntityType()
+				: Collections.singleton(associationTargetType);
 	}
 
 	/* 
@@ -159,4 +183,24 @@ class JpaPersistentPropertyImpl extends AnnotationBasedPersistentProperty<JpaPer
 	protected Association<JpaPersistentProperty> createAssociation() {
 		return new Association<JpaPersistentProperty>(this, null);
 	}
+
+	/**
+	 * Inspects the association annotations on the property and returns the target entity type if specified.
+	 * 
+	 * @return
+	 */
+	private TypeInformation<?> detectAssociationTargetType() {
+
+		for (Class<? extends Annotation> associationAnnotation : ASSOCIATION_ANNOTATIONS) {
+
+			Annotation annotation = findAnnotation(associationAnnotation);
+			Object targetEntity = AnnotationUtils.getValue(annotation, "targetEntity");
+
+			if (targetEntity != null && !void.class.equals(targetEntity)) {
+				return ClassTypeInformation.from((Class<?>) targetEntity);
+			}
+		}
+
+		return null;
+	}
 }

src/test/java/org/springframework/data/jpa/mapping/JpaPersistentPropertyImplUnitTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2014 the original author or authors.
+ * Copyright 2013-2015 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.
@@ -15,11 +15,12 @@
  */
 package org.springframework.data.jpa.mapping;
 
-import static org.hamcrest.CoreMatchers.*;
+import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
 import javax.persistence.Embeddable;
 import javax.persistence.Embedded;
+import javax.persistence.ManyToOne;
 import javax.persistence.OneToOne;
 import javax.persistence.Transient;
 import javax.persistence.metamodel.Metamodel;
@@ -92,6 +93,24 @@ public class JpaPersistentPropertyImplUnitTests {
 		assertThat(entity.getPersistentProperty("embedded").isAssociation(), is(true));
 	}
 
+	/**
+	 * @see DATAJPA-664
+	 */
+	@Test
+	public void considersTargetEntityTypeForPropertyType() {
+
+		JpaPersistentProperty property = getProperty(SpecializedAssociation.class, "api");
+
+		assertThat(property.getType(), is(typeCompatibleWith(Api.class)));
+		assertThat(property.getActualType(), is(typeCompatibleWith(Implementation.class)));
+	}
+
+	private JpaPersistentProperty getProperty(Class<?> ownerType, String propertyName) {
+
+		JpaPersistentEntity<?> entity = context.getPersistentEntity(ownerType);
+		return entity.getPersistentProperty(propertyName);
+	}
+
 	static class Sample {
 
 		@OneToOne Sample other;
@@ -108,4 +127,15 @@ public class JpaPersistentPropertyImplUnitTests {
 	static class SampleEmbedded {
 
 	}
+
+	// DATAJPA-664
+
+	static class SpecializedAssociation {
+
+		@ManyToOne(targetEntity = Implementation.class) Api api;
+	}
+
+	static interface Api {}
+
+	static class Implementation {}
 }