DATAMONGO-1509 - Write type hint as last element of a Document.

Always add type hint as last property of a Document.
This is necessary to assure document equality within MongoDB in cases where the query contains full document comparisons. Unfortunately this also might break existing stuff since the order of properties within a Document is changed with this commit.

Original pull request: spring-projects#411.

Author: christophstrobl

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

@@ -359,20 +359,20 @@ public void write(final Object obj, final Bson bson) {
 			return;
 		}
 
-		Class<?> entityType = obj.getClass();
-		boolean handledByCustomConverter = conversions.getCustomWriteTarget(entityType, Document.class) != null;
+		Class<?> entityType = ClassUtils.getUserClass(obj.getClass());
 		TypeInformation<? extends Object> type = ClassTypeInformation.from(entityType);
 
-		if (!handledByCustomConverter && !(bson instanceof Collection)) {
-			typeMapper.writeType(type, bson);
-		}
-
 		Object target = obj instanceof LazyLoadingProxy ? ((LazyLoadingProxy) obj).getTarget() : obj;
 
 		writeInternal(target, bson, type);
 		if (asMap(bson).containsKey("_is") && asMap(bson).get("_id") == null) {
 			removeFromMap(bson, "_id");
 		}
+
+		boolean handledByCustomConverter = conversions.getCustomWriteTarget(entityType, Document.class) != null;
+		if (!handledByCustomConverter && !(bson instanceof Collection)) {
+			typeMapper.writeType(type, bson);
+		}
 	}
 
 	/**
@@ -529,12 +529,12 @@ protected void writePropertyInternal(Object obj, Bson bson, MongoPersistentPrope
 
 		Object existingValue = accessor.get(prop);
 		Document document = existingValue instanceof Document ? (Document) existingValue : new Document();
-		addCustomTypeKeyIfNecessary(ClassTypeInformation.from(prop.getRawType()), obj, document);
 
 		MongoPersistentEntity<?> entity = isSubtype(prop.getType(), obj.getClass())
 				? mappingContext.getPersistentEntity(obj.getClass()) : mappingContext.getPersistentEntity(type);
 
 		writeInternal(obj, document, entity);
+		addCustomTypeKeyIfNecessary(ClassTypeInformation.from(prop.getRawType()), obj, document);
 		accessor.put(prop, document);
 	}
 

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

@@ -18,6 +18,7 @@
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
+import java.util.Iterator;
 import java.util.List;
 
 import org.bson.Document;
@@ -80,4 +81,23 @@ public static <T> T getTypedValue(Document source, String key, Class<T> type) {
 
 		return (T) value;
 	}
+
+	public static void assertTypeHint(Document document, Class<?> type) {
+		assertTypeHint(document, type.getName());
+	}
+
+	public static void assertTypeHint(Document document, String expectedTypeString) {
+
+		Iterator<String> keyIterator = document.keySet().iterator();
+		while (keyIterator.hasNext()) {
+			String key = keyIterator.next();
+			if (key.equals("_class")) {
+				assertThat((String) document.get(key), is(equalTo(expectedTypeString)));
+				assertThat(keyIterator.hasNext(), is(false));
+				return;
+			}
+		}
+
+		fail(String.format("Expected to find type info %s in %s.", document, expectedTypeString));
+	}
 }

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

@@ -44,6 +44,7 @@
 import org.joda.time.DateTime;
 import org.junit.After;
 import org.junit.Before;
+import org.junit.Ignore;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
@@ -3486,6 +3487,22 @@ public void onBeforeSave(BeforeSaveEvent<Document> event) {
 		assertThat(document.id, is(notNullValue()));
 	}
 
+
+	/**
+	 * @see DATAMONGO-1509
+	 */
+	@Test
+	public void findsByGnericNestedListElements() {
+
+		List<Model> modelList = Arrays.<Model>asList(new ModelA("value"));
+		DocumentWithCollection dwc = new DocumentWithCollection(modelList);
+
+		template.insert(dwc);
+
+		Query query = query(where("models").is(modelList));
+		assertThat(template.findOne(query, DocumentWithCollection.class), is(equalTo(dwc)));
+	}
+
 	static class TypeWithNumbers {
 
 		@Id String id;
@@ -3565,6 +3582,7 @@ static class DocumentWithDBRefCollection {
 		@org.springframework.data.mongodb.core.mapping.DBRef(lazy = true) public Map<String, Sample> lazyDbRefAnnotatedMap;
 	}
 
+	@EqualsAndHashCode
 	static class DocumentWithCollection {
 
 		@Id String id;
@@ -3617,6 +3635,7 @@ static interface Model {
 		String id();
 	}
 
+	@EqualsAndHashCode
 	static class ModelA implements Model {
 
 		@Id String id;

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

@@ -526,6 +526,9 @@ public void maybeConvertHandlesNullValuesCorrectly() {
 		assertThat(converter.convertToMongoType(null), is(nullValue()));
 	}
 
+	/**
+	 * @see DATAMONGO-1509
+	 */
 	@Test
 	public void writesGenericTypeCorrectly() {
 
@@ -537,7 +540,7 @@ public void writesGenericTypeCorrectly() {
 		converter.write(type, result);
 
 		org.bson.Document content = (org.bson.Document) result.get("content");
-		assertThat(content.get("_class"), is(notNullValue()));
+		assertTypeHint(content, Address.class);
 		assertThat(content.get("city"), is(notNullValue()));
 	}
 
@@ -1272,6 +1275,7 @@ public void eagerlyReturnsDBRefObjectIfTargetAlreadyIsOne() {
 
 	/**
 	 * @see DATAMONGO-523
+	 * @see DATAMONGO-1509
 	 */
 	@Test
 	public void considersTypeAliasAnnotation() {
@@ -1282,9 +1286,7 @@ public void considersTypeAliasAnnotation() {
 		org.bson.Document result = new org.bson.Document();
 		converter.write(aliased, result);
 
-		Object type = result.get("_class");
-		assertThat(type, is(notNullValue()));
-		assertThat(type.toString(), is("_"));
+		assertTypeHint(result, "_");
 	}
 
 	/**
@@ -1409,6 +1411,7 @@ public void writesProjectingTypeCorrectly() {
 	/**
 	 * @see DATAMONGO-812
 	 * @see DATAMONGO-893
+	 * @see DATAMONGO-1509
 	 */
 	@Test
 	public void convertsListToBasicDBListAndRetainsTypeInformationForComplexObjects() {
@@ -1424,7 +1427,7 @@ public void convertsListToBasicDBListAndRetainsTypeInformationForComplexObjects(
 
 		List<Object> dbList = (List<Object>) result;
 		assertThat(dbList, hasSize(1));
-		assertThat(getTypedValue(getAsDocument(dbList, 0), "_class", String.class), equalTo(Address.class.getName()));
+		assertTypeHint(getAsDocument(dbList, 0), Address.class);
 	}
 
 	/**
@@ -1444,6 +1447,7 @@ public void convertsListToBasicDBListWithoutTypeInformationForSimpleTypes() {
 
 	/**
 	 * @see DATAMONGO-812
+	 * @see DATAMONGO-1509
 	 */
 	@Test
 	public void convertsArrayToBasicDBListAndRetainsTypeInformationForComplexObjects() {
@@ -1458,7 +1462,7 @@ public void convertsArrayToBasicDBListAndRetainsTypeInformationForComplexObjects
 
 		List<Object> dbList = (List<Object>) result;
 		assertThat(dbList, hasSize(1));
-		assertThat(getTypedValue(getAsDocument(dbList, 0), "_class", String.class), equalTo(Address.class.getName()));
+		assertTypeHint(getAsDocument(dbList, 0), Address.class);
 	}
 
 	/**
@@ -1802,6 +1806,7 @@ public void shouldIncludeTextScorePropertyWhenReading() {
 
 	/**
 	 * @see DATAMONGO-1001
+	 * @see DATAMONGO-1509
 	 */
 	@Test
 	public void shouldWriteCglibProxiedClassTypeInformationCorrectly() {
@@ -1814,7 +1819,7 @@ public void shouldWriteCglibProxiedClassTypeInformationCorrectly() {
 		org.bson.Document document = new org.bson.Document();
 		converter.write(proxied, document);
 
-		assertThat(document.get("_class"), is((Object) GenericType.class.getName()));
+		assertTypeHint(document, GenericType.class);
 	}
 
 	/**