DATAJPA-50 - Introduced support for usage of @IdClass.

Introduced to support @IdClass to define entity ids. The JpeMetamodelEntityInformation builds instances of the annotated @IdClass in case any of the attributes of the entity declared in the @IdClass has a non-null value.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011 the original author or authors.
+ * Copyright 2011-2012 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.
@@ -17,14 +17,21 @@
 
 import java.io.Serializable;
 import java.lang.reflect.Field;
-import java.lang.reflect.Member;
-import java.lang.reflect.Method;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.Set;
 
+import javax.persistence.IdClass;
 import javax.persistence.metamodel.IdentifiableType;
 import javax.persistence.metamodel.ManagedType;
 import javax.persistence.metamodel.Metamodel;
 import javax.persistence.metamodel.SingularAttribute;
 
+import org.springframework.beans.BeanWrapper;
+import org.springframework.beans.BeanWrapperImpl;
+import org.springframework.beans.BeansException;
+import org.springframework.beans.NotReadablePropertyException;
+import org.springframework.beans.NotWritablePropertyException;
 import org.springframework.data.repository.core.EntityInformation;
 import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
@@ -37,13 +44,13 @@
 public class JpaMetamodelEntityInformation<T, ID extends Serializable> extends JpaEntityInformationSupport<T, ID>
 		implements JpaEntityInformation<T, ID> {
 
-	private final SingularAttribute<? super T, ?> attribute;
+	private final IdMetadata<T> idMetadata;
 
 	/**
 	 * Creates a new {@link JpaMetamodelEntityInformation} for the given domain class and {@link Metamodel}.
 	 * 
-	 * @param domainClass
-	 * @param metamodel
+	 * @param domainClass must not be {@literal null}.
+	 * @param metamodel must not be {@@iteral null}.
 	 */
 	public JpaMetamodelEntityInformation(Class<T> domainClass, Metamodel metamodel) {
 
@@ -60,21 +67,36 @@ public JpaMetamodelEntityInformation(Class<T> domainClass, Metamodel metamodel)
 			throw new IllegalArgumentException("The given domain class does not contain an id attribute!");
 		}
 
-		IdentifiableType<T> identifiableType = (IdentifiableType<T>) type;
-		this.attribute = identifiableType.getId(identifiableType.getIdType().getJavaType());
+		this.idMetadata = new IdMetadata<T>((IdentifiableType<T>) type);
 	}
 
 	/*
 	 * (non-Javadoc)
-	 * 
-	 * @see
-	 * org.springframework.data.repository.support.IdAware#getId(java.lang.Object
-	 * )
+	 * @see org.springframework.data.repository.core.EntityInformation#getId(java.lang.Object)
 	 */
 	@SuppressWarnings("unchecked")
 	public ID getId(T entity) {
 
-		return (ID) getMemberValue(attribute.getJavaMember(), entity);
+		BeanWrapper entityWrapper = new DirectFieldAccessFallbackBeanWrapper(entity);
+
+		if (idMetadata.hasSimpleId()) {
+			return (ID) entityWrapper.getPropertyValue(idMetadata.getSimpleIdAttribute().getName());
+		}
+
+		BeanWrapper idWrapper = new DirectFieldAccessFallbackBeanWrapper(idMetadata.getType());
+		boolean partialIdValueFound = false;
+
+		for (SingularAttribute<? super T, ?> attribute : idMetadata) {
+			Object propertyValue = entityWrapper.getPropertyValue(attribute.getName());
+
+			if (propertyValue != null) {
+				partialIdValueFound = true;
+			}
+
+			idWrapper.setPropertyValue(attribute.getName(), propertyValue);
+		}
+
+		return (ID) (partialIdValueFound ? idWrapper.getWrappedInstance() : null);
 	}
 
 	/*
@@ -85,40 +107,109 @@ public ID getId(T entity) {
 	 */
 	@SuppressWarnings("unchecked")
 	public Class<ID> getIdType() {
+		return (Class<ID>) idMetadata.getType();
+	}
 
-		return (Class<ID>) attribute.getJavaType();
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see org.springframework.data.jpa.repository.support.JpaEntityMetadata#
+	 * getIdAttribute()
+	 */
+	public SingularAttribute<? super T, ?> getIdAttribute() {
+		return idMetadata.getSimpleIdAttribute();
 	}
 
 	/**
-	 * Returns the value of the given {@link Member} of the given {@link Object} .
+	 * Simple value object to encapsulate id specific metadata.
 	 * 
-	 * @param member
-	 * @param source
-	 * @return
+	 * @author Oliver Gierke
 	 */
-	private static Object getMemberValue(Member member, Object source) {
-
-		if (member instanceof Field) {
-			Field field = (Field) member;
-			ReflectionUtils.makeAccessible(field);
-			return ReflectionUtils.getField(field, source);
-		} else if (member instanceof Method) {
-			Method method = (Method) member;
-			ReflectionUtils.makeAccessible(method);
-			return ReflectionUtils.invokeMethod(method, source);
+	private static class IdMetadata<T> implements Iterable<SingularAttribute<? super T, ?>> {
+
+		private final IdentifiableType<T> type;
+		private final Set<SingularAttribute<? super T, ?>> attributes;
+
+		@SuppressWarnings("unchecked")
+		public IdMetadata(IdentifiableType<T> source) {
+
+			this.type = source;
+			this.attributes = (Set<SingularAttribute<? super T, ?>>) (source.hasSingleIdAttribute() ? Collections
+					.singleton(source.getId(source.getIdType().getJavaType())) : source.getIdClassAttributes());
 		}
 
-		throw new IllegalArgumentException("Given member is neither Field nor Method!");
+		public boolean hasSimpleId() {
+			return attributes.size() == 1;
+		}
+
+		public Class<?> getType() {
+
+			try {
+				return type.getIdType().getJavaType();
+			} catch (IllegalStateException e) {
+				// see https://hibernate.onjira.com/browse/HHH-6951
+				IdClass annotation = type.getJavaType().getAnnotation(IdClass.class);
+				return annotation == null ? null : annotation.value();
+			}
+		}
+
+		public SingularAttribute<? super T, ?> getSimpleIdAttribute() {
+			return attributes.iterator().next();
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see java.lang.Iterable#iterator()
+		 */
+		public Iterator<SingularAttribute<? super T, ?>> iterator() {
+			return attributes.iterator();
+		}
 	}
 
-	/*
-	 * (non-Javadoc)
+	/**
+	 * Custom extension of {@link BeanWrapperImpl} that falls back to direct field access in case the object or type being
+	 * wrapped does not use accessor methods.
 	 * 
-	 * @see org.springframework.data.jpa.repository.support.JpaEntityMetadata#
-	 * getIdAttribute()
+	 * @author Oliver Gierke
 	 */
-	public SingularAttribute<? super T, ?> getIdAttribute() {
+	private static class DirectFieldAccessFallbackBeanWrapper extends BeanWrapperImpl {
+
+		public DirectFieldAccessFallbackBeanWrapper(Object entity) {
+			super(entity);
+		}
 
-		return attribute;
+		public DirectFieldAccessFallbackBeanWrapper(Class<?> type) {
+			super(type);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.beans.BeanWrapperImpl#getPropertyValue(java.lang.String)
+		 */
+		@Override
+		public Object getPropertyValue(String propertyName) throws BeansException {
+			try {
+				return super.getPropertyValue(propertyName);
+			} catch (NotReadablePropertyException e) {
+				Field field = ReflectionUtils.findField(getWrappedClass(), propertyName);
+				ReflectionUtils.makeAccessible(field);
+				return ReflectionUtils.getField(field, getWrappedInstance());
+			}
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.beans.BeanWrapperImpl#setPropertyValue(java.lang.String, java.lang.Object)
+		 */
+		@Override
+		public void setPropertyValue(String propertyName, Object value) throws BeansException {
+			try {
+				super.setPropertyValue(propertyName, value);
+			} catch (NotWritablePropertyException e) {
+				Field field = ReflectionUtils.findField(getWrappedClass(), propertyName);
+				ReflectionUtils.makeAccessible(field);
+				ReflectionUtils.setField(field, getWrappedInstance(), value);
+			}
+		}
 	}
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2011 the original author or authors.
+ * Copyright 2008-2012 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.
@@ -195,16 +195,20 @@ public boolean exists(ID id) {
 
 		Assert.notNull(id, "The given id must not be null!");
 
-		String placeholder = provider.getCountQueryPlaceholder();
-		String entityName = entityInformation.getEntityName();
-		String idAttributeName = entityInformation.getIdAttribute().getName();
+		if (entityInformation.getIdAttribute() != null) {
 
-		String existsQuery = String.format(EXISTS_QUERY_STRING, placeholder, entityName, idAttributeName);
+			String placeholder = provider.getCountQueryPlaceholder();
+			String entityName = entityInformation.getEntityName();
+			String idAttributeName = entityInformation.getIdAttribute().getName();
+			String existsQuery = String.format(EXISTS_QUERY_STRING, placeholder, entityName, idAttributeName);
 
-		TypedQuery<Long> query = em.createQuery(existsQuery, Long.class);
-		query.setParameter("id", id);
+			TypedQuery<Long> query = em.createQuery(existsQuery, Long.class);
+			query.setParameter("id", id);
 
-		return query.getSingleResult() == 1;
+			return query.getSingleResult() == 1;
+		} else {
+			return findOne(id) != null;
+		}
 	}
 
 	/*

src/test/java/org/springframework/data/jpa/domain/sample/SampleWithIdClass.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2012 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.jpa.domain.sample;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.IdClass;
+
+import org.springframework.data.domain.Persistable;
+
+/**
+ * Sample entity using {@link IdClass} annotation to demarcate ids.
+ * 
+ * @author Oliver Gierke
+ */
+@Entity
+@IdClass(SampleWithIdClassPK.class)
+public class SampleWithIdClass implements Persistable<SampleWithIdClassPK> {
+
+	private static final long serialVersionUID = 1L;
+
+	@Id
+	Long first;
+
+	@Id
+	Long second;
+
+	private boolean isNew;
+
+	protected SampleWithIdClass() {
+		this.isNew = true;
+	}
+
+	public SampleWithIdClass(Long first, Long second) {
+		this.first = first;
+		this.second = second;
+		this.isNew = true;
+	}
+
+	/**
+	 * @return the first
+	 */
+	public Long getFirst() {
+		return first;
+	}
+
+	/**
+	 * @return the second
+	 */
+	public Long getSecond() {
+		return second;
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.domain.Persistable#getId()
+	 */
+	public SampleWithIdClassPK getId() {
+		return new SampleWithIdClassPK(first, second);
+	}
+
+	/* (non-Javadoc)
+	 * @see org.springframework.data.domain.Persistable#isNew()
+	 */
+	public boolean isNew() {
+		return this.isNew;
+	}
+
+	public void setNotNew() {
+		this.isNew = false;
+	}
+}