How would I do $push using MongoRepository in Spring Data?

Question

I have a MongoDB structure like this:

record = { 'field': 'value', 
           'field2': 'value2',
           'events' : [ { 'event1': 1 }, { 'event2' : 2 }]
         }

I am using Spring Data MongoDB package to access this data. There will be mainly writes to the data, so I would like to use the native "$push" functionality to add "events" to the "record", but I can't seem to figure out how to do it with MongoRepository without fetching the entire record and then pushing it and saving it back?

When doing using MongoRepository, you never really have a concrete implementation. Spring handles everything based on annotations or the names of the methods themselves

UPDATE

Would the correct way to be to implement a custom method on the repository and then use MongoTemplate to do it manually?

Example:

FooRepository.java

public interface FooRepository extends
    CrudRepository<Foo, ObjectId>,
        AppointmentWarehouseRepositoryCustom {
}

FooRepositoryCustom.java

public interface AppointmentWarehouseRepositoryCustom {
    public void pushMethod();
}

FooRepositoryImpl.java

public class FooRepositoryImpl implements
    AppointmentWarehouseRepositoryCustom {

    @Autowired
    protected MongoTemplate mongoTemplate;

    public void pushMethod() {
        // Push methods here. 
    }
}

Answer 1

Yes, you must implement a custom method on the repository and your push method would be something like this :

public class FooRepositoryImpl implements
    AppointmentWarehouseRepositoryCustom {

    @Autowired
    protected MongoTemplate mongoTemplate;

    public void pushMethod(String objectId, Object... events) {
        mongoTemplate.updateFirst(
            Query.query(Criteria.where("id").is(objectId)), 
            new Update().pushAll("events", events), Foo.class);
    }
}

Answer 2

You can do this but I ran into an issue where the "_class" field wasn't being preserved. The pushed object itself was run through the configured converter but for some reason the "_class" field of that pushed object wasn't written. However, if I injected the converter and wrote the object to a DBObject myself, then the "_class" field was preserved and written. The thus becomes:

public class FooRepositoryImpl implements
AppointmentWarehouseRepositoryCustom {

@Autowired
protected MongoTemplate mongoTemplate;

public void pushMethod(String objectId, Object event) {
    DBObject eventObj = new BasicDBObject();
    converter.write(event, eventObj);
    mongoTemplate.updateFirst(
        Query.query(Criteria.where("id").is(objectId)), 
        new Update().push("events", eventObj), Foo.class);
  }
}