Query MongoDb based on Map Key Spring Repository - spring

Question

I need help to query nested documents. Using Spring Boot with MongoDB.
Structure:
public class Holiday {
#Id
private String id;
private Integer year;
private Map<String, List<HolidayElement>> holidays = new HashMap<>();
}
public class HolidayElement {
private String name;
#JsonFormat(pattern="yyyy-MM-dd")
private Date date;
private String note;
}
After saving everything the Json looks like:
[
{
"id": "5a153331b3cb1f0001e1edeb",
"year": 2017,
"holidays": {
"BB": [
{
"name": "Neujahrstag",
"date": "2017-01-01",
"note": ""
},
...
],
"HH": [
{ ... }
]
}
]
Now how can I get for instance: List of "HolidayElement" where the State is "BB"?

Answer 1

Assuming you have a repository like HolidayRepository, you need to create a custom implementation since you want to use MongoTemplate. So your HolidayRepository will look like
#Repository
public interface HolidayRepository extends MongoRepository<Holiday, String>, HolidayRepositoryCustom {
}
And declare two new files HolidayRepositoryCustom and HolidayRepositoryImpl in the same directory(very important) as HolidayRepository
public interface HolidayRepositoryCustom {
List<HolidayElement> findByMapId(final String mapId);
}
And the Impl class will look like this
public class HolidayRepositoryImpl implements HolidayRepositoryCustom {
private final MongoTemplate mongoTemplate;
#Autowired
public HolidayRepositoryImpl(final MongoTemplate mongoTemplate) {
this.mongoTemplate = mongoTemplate;
}
#Override
public List<HolidayElement> findByMapId(String mapId) {
final QueryBuilder queryBuilder = QueryBuilder.start();
queryBuilder
.and("holidays."+mapId).exists(true);
final DBObject projection = new BasicDBObject();
projection.put("holidays."+mapId, 1);
String collectionName = "Holiday";//Change to your collection name
try( final DBCursor dbCursor = mongoTemplate.getCollection(collectionName).find(queryBuilder.get(), projection)){
if(dbCursor.hasNext()){
DBObject next = dbCursor.next();
Map<String, List<HolidayElement>> holidayElements =
(Map<String, List<HolidayElement>>) next.get("holidays");
return holidayElements.get(mapId);
}
}
return Lists.newArrayList();
}
}