DATAMONGO-884 - Fix potential NullPointerException for lazy DBRefs.

We now initialize the proxy in case an Object-method is called that is overridden in the traget class. Removed the additional check for initialization and to-DBRef-methods as they're repeated in the target method.

Original pull requests: spring-projects#152, spring-projects#153.

Author: Thomas Darimont

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/DefaultDbRefResolver.java

@@ -15,6 +15,8 @@
  */
 package org.springframework.data.mongodb.core.convert;
 
+import static org.springframework.util.ReflectionUtils.*;
+
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
@@ -39,7 +41,6 @@
 import org.springframework.data.mongodb.core.mapping.MongoPersistentProperty;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
-import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
 
 import com.mongodb.DB;
@@ -211,15 +212,6 @@ public LazyLoadingInterceptor(MongoPersistentProperty property, DBRef dbref,
 		 */
 		@Override
 		public Object invoke(MethodInvocation invocation) throws Throwable {
-
-			if (invocation.getMethod().equals(INITIALIZE_METHOD)) {
-				return ensureResolved();
-			}
-
-			if (invocation.getMethod().equals(TO_DBREF_METHOD)) {
-				return this.dbref;
-			}
-
 			return intercept(invocation.getThis(), invocation.getMethod(), invocation.getArguments(), null);
 		}
 
@@ -238,7 +230,10 @@ public Object intercept(Object obj, Method method, Object[] args, MethodProxy pr
 				return this.dbref;
 			}
 
-			return ReflectionUtils.isObjectMethod(method) ? method.invoke(obj, args) : method.invoke(ensureResolved(), args);
+			Object target = isObjectMethod(method) && Object.class.equals(method.getDeclaringClass()) ? obj
+					: ensureResolved();
+
+			return method.invoke(target, args);
 		}
 
 		/**

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/DbRefMappingMongoConverterUnitTests.java

@@ -53,6 +53,7 @@
  * Unit tests dor {@link DbRefMappingMongoConverterUnitTests}.
  * 
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 @RunWith(MockitoJUnitRunner.class)
 public class DbRefMappingMongoConverterUnitTests {
@@ -285,6 +286,62 @@ public void lazyLoadingProxyForSerializableLazyDbRefOnConcreteType() {
 		assertThat(deserializedResult.dbRefToSerializableTarget.getValue(), is(value));
 	}
 
+	/**
+	 * @see DATAMONGO-884
+	 */
+	@Test
+	public void lazyLoadingProxyForToStringObjectMethodOverridingDbref() {
+
+		String id = "42";
+		String value = "bubu";
+		MappingMongoConverter converterSpy = spy(converter);
+		doReturn(new BasicDBObject("_id", id).append("value", value)).when(converterSpy).readRef((DBRef) any());
+
+		BasicDBObject dbo = new BasicDBObject();
+		WithObjectMethodOverrideLazyDbRefs lazyDbRefs = new WithObjectMethodOverrideLazyDbRefs();
+		lazyDbRefs.dbRefToToStringObjectMethodOverride = new ToStringObjectMethodOverrideLazyDbRefTarget(id, value);
+		converterSpy.write(lazyDbRefs, dbo);
+
+		WithObjectMethodOverrideLazyDbRefs result = converterSpy.read(WithObjectMethodOverrideLazyDbRefs.class, dbo);
+
+		assertThat(result.dbRefToToStringObjectMethodOverride, is(notNullValue()));
+		assertProxyIsResolved(result.dbRefToToStringObjectMethodOverride, false);
+		assertThat(result.dbRefToToStringObjectMethodOverride.toString(), is(id + ":" + value));
+		assertProxyIsResolved(result.dbRefToToStringObjectMethodOverride, true);
+	}
+
+	/**
+	 * @see DATAMONGO-884
+	 */
+	@Test
+	public void lazyLoadingProxyForEqualsAndHashcodeObjectMethodOverridingDbref() {
+
+		String id = "42";
+		String value = "bubu";
+		MappingMongoConverter converterSpy = spy(converter);
+		doReturn(new BasicDBObject("_id", id).append("value", value)).when(converterSpy).readRef((DBRef) any());
+
+		BasicDBObject dbo = new BasicDBObject();
+		WithObjectMethodOverrideLazyDbRefs lazyDbRefs = new WithObjectMethodOverrideLazyDbRefs();
+		lazyDbRefs.dbRefEqualsAndHashcodeObjectMethodOverride1 = new EqualsAndHashCodeObjectMethodOverrideLazyDbRefTarget(
+				id, value);
+		lazyDbRefs.dbRefEqualsAndHashcodeObjectMethodOverride2 = new EqualsAndHashCodeObjectMethodOverrideLazyDbRefTarget(
+				id, value);
+		converterSpy.write(lazyDbRefs, dbo);
+
+		WithObjectMethodOverrideLazyDbRefs result = converterSpy.read(WithObjectMethodOverrideLazyDbRefs.class, dbo);
+
+		assertProxyIsResolved(result.dbRefEqualsAndHashcodeObjectMethodOverride1, false);
+		assertThat(result.dbRefEqualsAndHashcodeObjectMethodOverride1, is(notNullValue()));
+		result.dbRefEqualsAndHashcodeObjectMethodOverride1.equals(null);
+		assertProxyIsResolved(result.dbRefEqualsAndHashcodeObjectMethodOverride1, true);
+
+		assertProxyIsResolved(result.dbRefEqualsAndHashcodeObjectMethodOverride2, false);
+		assertThat(result.dbRefEqualsAndHashcodeObjectMethodOverride2, is(notNullValue()));
+		result.dbRefEqualsAndHashcodeObjectMethodOverride2.hashCode();
+		assertProxyIsResolved(result.dbRefEqualsAndHashcodeObjectMethodOverride2, true);
+	}
+
 	private Object transport(Object result) {
 		return SerializationUtils.deserialize(SerializationUtils.serialize(result));
 	}
@@ -391,4 +448,73 @@ public SerializableLazyDbRefTarget(String id, String value) {
 
 		private static final long serialVersionUID = 1L;
 	}
+
+	static class ToStringObjectMethodOverrideLazyDbRefTarget extends LazyDbRefTarget {
+
+		private static final long serialVersionUID = 1L;
+
+		public ToStringObjectMethodOverrideLazyDbRefTarget() {}
+
+		public ToStringObjectMethodOverrideLazyDbRefTarget(String id, String value) {
+			super(id, value);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see java.lang.Object#toString()
+		 */
+		@Override
+		public String toString() {
+			return this.id + ":" + this.value;
+		}
+	}
+
+	static class EqualsAndHashCodeObjectMethodOverrideLazyDbRefTarget extends LazyDbRefTarget {
+
+		private static final long serialVersionUID = 1L;
+
+		public EqualsAndHashCodeObjectMethodOverrideLazyDbRefTarget() {}
+
+		public EqualsAndHashCodeObjectMethodOverrideLazyDbRefTarget(String id, String value) {
+			super(id, value);
+		}
+
+		@Override
+		public int hashCode() {
+			final int prime = 31;
+			int result = 1;
+			result = prime * result + ((id == null) ? 0 : id.hashCode());
+			result = prime * result + ((value == null) ? 0 : value.hashCode());
+			return result;
+		}
+
+		@Override
+		public boolean equals(Object obj) {
+			if (this == obj)
+				return true;
+			if (obj == null)
+				return false;
+			if (getClass() != obj.getClass())
+				return false;
+			EqualsAndHashCodeObjectMethodOverrideLazyDbRefTarget other = (EqualsAndHashCodeObjectMethodOverrideLazyDbRefTarget) obj;
+			if (id == null) {
+				if (other.id != null)
+					return false;
+			} else if (!id.equals(other.id))
+				return false;
+			if (value == null) {
+				if (other.value != null)
+					return false;
+			} else if (!value.equals(other.value))
+				return false;
+			return true;
+		}
+	}
+
+	static class WithObjectMethodOverrideLazyDbRefs {
+
+		@org.springframework.data.mongodb.core.mapping.DBRef(lazy = true) ToStringObjectMethodOverrideLazyDbRefTarget dbRefToToStringObjectMethodOverride;
+		@org.springframework.data.mongodb.core.mapping.DBRef(lazy = true) EqualsAndHashCodeObjectMethodOverrideLazyDbRefTarget dbRefEqualsAndHashcodeObjectMethodOverride2;
+		@org.springframework.data.mongodb.core.mapping.DBRef(lazy = true) EqualsAndHashCodeObjectMethodOverrideLazyDbRefTarget dbRefEqualsAndHashcodeObjectMethodOverride1;
+	}
 }