DATAMONGO-679 - Fixed saving plain JSON strings in MongoTemplate.

MongoTemplate.doSave(…) didn't handle plain JSON strings correctly. It now correctly passes the marshaled object to the underlying method.

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

@@ -798,7 +798,6 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 		}
 	}
 
-	@SuppressWarnings("unchecked")
 	protected <T> void doSave(String collectionName, T objectToSave, MongoWriter<T> writer) {
 
 		assertUpdateableIdIfNotSet(objectToSave);
@@ -811,7 +810,7 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 			writer.write(objectToSave, dbDoc);
 		} else {
 			try {
-				objectToSave = (T) JSON.parse((String) objectToSave);
+				dbDoc = (DBObject) JSON.parse((String) objectToSave);
 			} catch (JSONParseException e) {
 				throw new MappingException("Could not parse given String to save into a JSON document!", e);
 			}

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

@@ -1597,6 +1597,21 @@ public class MongoTemplateTests {
 		}
 	}
 
+	/**
+	 * @see DATAMONGO-679
+	 */
+	@Test
+	public void savesJsonStringCorrectly() {
+
+		DBObject dbObject = new BasicDBObject().append("first", "first").append("second", "second");
+
+		template.save(dbObject.toString(), "collection");
+
+		List<DBObject> result = template.findAll(DBObject.class, "collection");
+		assertThat(result.size(), is(1));
+		assertThat(result.get(0).containsField("first"), is(true));
+	}
+
 	static class MyId {
 
 		String first;