DATAMONGO-1287 - Fix double fetching for lazy DbRef used in ctor.

We now check properties for their usage as ctor arguments, that might already have been resolved, before setting the actual value. This prevents turning already eagerly fetched DBRefs back into LazyLoadingProxies.

Relates to original PR #322.

Author: christophstrobl

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

@@ -290,7 +290,9 @@ public void doWithAssociation(Association<MongoPersistentProperty> association)
 				final MongoPersistentProperty property = association.getInverse();
 				Object value = dbo.get(property.getFieldName());
 
-				if (value == null) {
+				if (value == null
+						|| (entity.getPersistenceConstructor().hasParameters() && entity.isConstructorArgument(property) && accessor
+								.getProperty(property) != null)) {
 					return;
 				}
 

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

@@ -197,6 +197,7 @@ protected void cleanDb() {
 		template.dropCollection(SomeTemplate.class);
 		template.dropCollection(Address.class);
 		template.dropCollection(DocumentWithCollectionOfSamples.class);
+		template.dropCollection(DocumentWithLazyDBrefUsedInPresistenceConstructor.class);
 	}
 
 	@Test
@@ -3035,7 +3036,7 @@ public void takesSortIntoAccountWhenStreaming() {
 	 */
 	@Test
 	public void takesLimitIntoAccountWhenStreaming() {
-		
+
 		Person youngestPerson = new Person("John", 20);
 		Person oldestPerson = new Person("Jane", 42);
 
@@ -3049,6 +3050,75 @@ public void takesLimitIntoAccountWhenStreaming() {
 		assertThat(stream.hasNext(), is(false));
 	}
 
+	/**
+	 * @see DATAMONGO-1287
+	 */
+	@Test
+	public void shouldReuseAlreadyResolvedLazyLoadedDBRefWhenUsedAsPersistenceConstrcutorArgument() {
+
+		Document docInCtor = new Document();
+		docInCtor.id = "doc-in-ctor";
+		template.save(docInCtor);
+
+		DocumentWithLazyDBrefUsedInPresistenceConstructor source = new DocumentWithLazyDBrefUsedInPresistenceConstructor(
+				docInCtor);
+
+		template.save(source);
+
+		DocumentWithLazyDBrefUsedInPresistenceConstructor loaded = template.findOne(query(where("id").is(source.id)),
+				DocumentWithLazyDBrefUsedInPresistenceConstructor.class);
+		assertThat(loaded.refToDocUsedInCtor, not(instanceOf(LazyLoadingProxy.class)));
+		assertThat(loaded.refToDocNotUsedInCtor, nullValue());
+	}
+
+	/**
+	 * @see DATAMONGO-1287
+	 */
+	@Test
+	public void shouldNotReuseLazyLoadedDBRefWhenTypeUsedInPersistenceConstrcutorButValueRefersToAnotherProperty() {
+
+		Document docNotUsedInCtor = new Document();
+		docNotUsedInCtor.id = "doc-but-not-used-in-ctor";
+		template.save(docNotUsedInCtor);
+
+		DocumentWithLazyDBrefUsedInPresistenceConstructor source = new DocumentWithLazyDBrefUsedInPresistenceConstructor(
+				null);
+		source.refToDocNotUsedInCtor = docNotUsedInCtor;
+
+		template.save(source);
+
+		DocumentWithLazyDBrefUsedInPresistenceConstructor loaded = template.findOne(query(where("id").is(source.id)),
+				DocumentWithLazyDBrefUsedInPresistenceConstructor.class);
+		assertThat(loaded.refToDocNotUsedInCtor, instanceOf(LazyLoadingProxy.class));
+		assertThat(loaded.refToDocUsedInCtor, nullValue());
+	}
+
+	/**
+	 * @see DATAMONGO-1287
+	 */
+	@Test
+	public void shouldRespectParamterValueWhenAttemptingToReuseLazyLoadedDBRefUsedInPersistenceConstrcutor() {
+
+		Document docInCtor = new Document();
+		docInCtor.id = "doc-in-ctor";
+		template.save(docInCtor);
+
+		Document docNotUsedInCtor = new Document();
+		docNotUsedInCtor.id = "doc-but-not-used-in-ctor";
+		template.save(docNotUsedInCtor);
+
+		DocumentWithLazyDBrefUsedInPresistenceConstructor source = new DocumentWithLazyDBrefUsedInPresistenceConstructor(
+				docInCtor);
+		source.refToDocNotUsedInCtor = docNotUsedInCtor;
+
+		template.save(source);
+
+		DocumentWithLazyDBrefUsedInPresistenceConstructor loaded = template.findOne(query(where("id").is(source.id)),
+				DocumentWithLazyDBrefUsedInPresistenceConstructor.class);
+		assertThat(loaded.refToDocUsedInCtor, not(instanceOf(LazyLoadingProxy.class)));
+		assertThat(loaded.refToDocNotUsedInCtor, instanceOf(LazyLoadingProxy.class));
+	}
+
 	static class DoucmentWithNamedIdField {
 
 		@Id String someIdKey;
@@ -3375,4 +3445,18 @@ static class SomeMessage {
 		@org.springframework.data.mongodb.core.mapping.DBRef SomeContent dbrefContent;
 		SomeContent normalContent;
 	}
+
+	static class DocumentWithLazyDBrefUsedInPresistenceConstructor {
+
+		@Id String id;
+		@org.springframework.data.mongodb.core.mapping.DBRef(lazy = true) Document refToDocUsedInCtor;
+		@org.springframework.data.mongodb.core.mapping.DBRef(lazy = true) Document refToDocNotUsedInCtor;
+
+		@PersistenceConstructor
+		public DocumentWithLazyDBrefUsedInPresistenceConstructor(Document refToDocUsedInCtor) {
+			this.refToDocUsedInCtor = refToDocUsedInCtor;
+		}
+
+	}
+
 }