DATAMONGO-1176 - Exclude null id fields in bulk insert.

We no longer map _id fields into Document that are null to enforce MongoDB ObjectId generation on batch insert like insertAll.

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

@@ -938,13 +938,12 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware,
 		for (T o : batchToSave) {
 
 			initializeVersionProperty(o);
-			Document dbDoc = new Document();
 
 			maybeEmitEvent(new BeforeConvertEvent<T>(o, collectionName));
-			writer.write(o, dbDoc);
+			Document document = toDocument(o, writer);
 
-			maybeEmitEvent(new BeforeSaveEvent<T>(o, dbDoc, collectionName));
-			documentList.add(dbDoc);
+			maybeEmitEvent(new BeforeSaveEvent<T>(o, document, collectionName));
+			documentList.add(document);
 		}
 
 		List<Object> ids = consolidateIdentifiers(insertDocumentList(collectionName, documentList), documentList);

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

@@ -3026,6 +3026,24 @@ public class MongoTemplateTests {
 		assertThat(result, hasItems(newYork, washington));
 	}
 
+	/**
+	 * @see DATAMONGO-1176
+	 */
+	@Test
+	public void generatesIdForInsertAll() {
+
+		Person walter = new Person(null, "Walter");
+		Person jesse = new Person(null, "Jesse");
+
+		template.insertAll(Arrays.asList(walter, jesse));
+
+		List<Person> result = template.findAll(Person.class);
+
+		assertThat(result, hasSize(2));
+		assertThat(walter.getId(), is(notNullValue()));
+		assertThat(jesse.getId(), is(notNullValue()));
+	}
+
 	/**
 	 * @see DATAMONGO-1208
 	 */