DATAJPA-1576 - JpaMetamodelEntityInformation uses getters to access ids from proxies.

Note that it still uses field access for non proxy entities.

Signed-off-by: Jens Schauder <jschauder@pivotal.io>
Original pull request: #421.

src/main/java/org/springframework/data/jpa/repository/support/JpaMetamodelEntityInformation.java

@@ -35,6 +35,7 @@ import javax.persistence.metamodel.Type.PersistenceType;
 import org.springframework.beans.BeanWrapper;
 import org.springframework.beans.BeanWrapperImpl;
 import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.data.jpa.provider.PersistenceProvider;
 import org.springframework.data.jpa.util.JpaMetamodel;
 import org.springframework.data.util.DirectFieldAccessFallbackBeanWrapper;
 import org.springframework.data.util.ProxyUtils;
@@ -147,6 +148,14 @@ public class JpaMetamodelEntityInformation<T, ID> extends JpaEntityInformationSu
 	@SuppressWarnings("unchecked")
 	public ID getId(T entity) {
 
+		// check if this is a proxy. If so use Proxy mechanics to access the id.
+		PersistenceProvider persistenceProvider = PersistenceProvider.fromMetamodel(metamodel);
+
+		if (persistenceProvider.shouldUseAccessorFor(entity)) {
+			return (ID) persistenceProvider.getIdentifierFrom(entity);
+		}
+
+		// if not a proxy use Spring mechanics to access the id.
 		BeanWrapper entityWrapper = new DirectFieldAccessFallbackBeanWrapper(entity);
 
 		if (idMetadata.hasSimpleId()) {

src/test/java/org/springframework/data/jpa/repository/support/JpaMetamodelEntityInformationIntegrationTests.java

@@ -301,6 +301,22 @@ public class JpaMetamodelEntityInformationIntegrationTests {
 		assertThat(pk.getSecond()).isEqualTo(42L);
 	}
 
+	@Test // DATAJPA-1576
+	@Ignore
+	public void prefersPrivateGetterOverFieldAccess() {
+
+		EntityManagerFactory emf = Persistence.createEntityManagerFactory(getMetadadataPersitenceUnitName());
+		EntityManager em = emf.createEntityManager();
+
+		JpaEntityInformation<EntityWithPrivateIdGetter, ?> information = getEntityInformation(EntityWithPrivateIdGetter.class, em);
+
+		EntityWithPrivateIdGetter entity = new EntityWithPrivateIdGetter();
+
+		Object id = information.getId(entity);
+
+		assertThat(id).isEqualTo(42L);
+	}
+
 	protected String getMetadadataPersitenceUnitName() {
 		return "metadata";
 	}
@@ -358,4 +374,19 @@ public class JpaMetamodelEntityInformationIntegrationTests {
 		Long id;
 		EntityWithIdClassPK reference;
 	}
+
+	@Entity
+	public static class EntityWithPrivateIdGetter implements Serializable{
+
+		private long id = 0;
+
+		@Id
+		private long getId() {
+			return 42;
+		}
+
+		public void setId(long id) {
+			this.id = id;
+		}
+	}
 }

src/test/resources/META-INF/persistence.xml

@@ -100,6 +100,7 @@
 		<class>org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformationIntegrationTests$Sample</class>
 		<class>org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformationIntegrationTests$EntityWithNestedIdClass</class>
 		<class>org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformationIntegrationTests$EntityWithIdClass</class>
+		<class>org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformationIntegrationTests$EntityWithPrivateIdGetter</class>
 		<exclude-unlisted-classes>true</exclude-unlisted-classes>
 		<properties>
 			<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect" />