通过Morphia（MongoDB）推送到嵌入式子文档中的数组

Question

TL;DR I wish to push a list of objects to an array in mongodb; this array is nested in an embedded subdocument, and I don't know how to reach this array, without first retrieving the entire main document from the database.

First, my main entity:

@Entity("trackers")
public class Tracker {

    @Id
    private ObjectId id;
    private String ican;
    @Embedded
    private List<Day> days;

    //getters, setters & constructors
}

A Day object looks like this:

@Embedded
public class Day {

    private LocalDate date;
    @Embedded
    private List<GeoStamp> geoStamps;

    //getters, setters & constructors
}

And lastly, a geostamp object looks like this:

@Embedded
public class GeoStamp {

    private Date dateTime;
    private double latitude;
    private double longitude;

    //getters, setters & constructors
}

Now, in my database this ends up looking like this:

{
    "_id" : ObjectId("58ee636b44e7ed48200ee8d4"),
    "className" : "com.model.Tracker",
    "ican" : "NL 12346",
    "days" : [
        {
            "date" : ISODate("2017-04-11T22:00:00Z"),
            "geoStamps" : [
                {
                    "dateTime" : ISODate("2017-04-12T17:27:07.249Z"),
                    "latitude" : 23.2222,
                    "longitude" : 44.333
                },
                {
                    "dateTime" : ISODate("2017-04-12T17:27:07.249Z"),
                    "latitude" : 23.2222,
                    "longitude" : 44.333
                },
                {
                    "dateTime" : ISODate("2017-04-12T17:27:07.249Z"),
                    "latitude" : 23.2222,
                    "longitude" : 44.333
                }
            ]
        },
        {
            "date" : ISODate("2017-01-01T23:00:00Z"),
            "geoStamps" : [
                {
                    "dateTime" : ISODate("2017-04-12T17:27:07.249Z"),
                    "latitude" : 23.2222,
                    "longitude" : 44.333
                },
                {
                    "dateTime" : ISODate("2017-04-12T17:27:07.249Z"),
                    "latitude" : 23.2222,
                    "longitude" : 44.333
                },
                {
                    "dateTime" : ISODate("2017-04-12T17:27:07.249Z"),
                    "latitude" : 23.2222,
                    "longitude" : 44.333
                }
            ]
        }
    ]
}

Now what I wish to do is push a list of GeoStamps to a GeoStamp array in Mongo, where I first filter on either the ObjectId of a Tracker, or its ican. Then within the document found I need to filter by day, so I don't add the GeoStamp list to multiple GeoStamp arrays spread out over multiple dates.

I thought to be able to do it in the following way:

My query (yes I know retrievedFields is deprecated and I'd rather not use it, but this was my solution that came closest to working):

final Query<Tracker> trackerQuery = datastore.find(Tracker.class)
                .filter("_id", id)
                .filter("days.date", LocalDate.now())
                .retrievedFields(true, "days.$");

My updateOperations (newGeoStamps is the list of GeoStamp objects to be added):

final UpdateOperations<Tracker> trackerUpdate = datastore.createUpdateOperations(Tracker.class).push("days.geoStamps", newGeoStamps);

And lastly, updateResults:

final UpdateResults trackerUpdateResults = datastore.update(trackerQuery, trackerUpdate);

This throws a WriteConcernException with the following error:

Write failed with error code 16837 and error message 'cannot use the part (days of days.geoStamps) to traverse the element ({days: [ { date: new Date(1491948000000), geoStamps: [ { dateTime: new Date(1492019739661), latitude: 23.2222, longitude: 44.333 }, { dateTime: new Date(1492019739661), latitude: 23.2222, longitude: 44.333 }, { dateTime: new Date(1492019739661), latitude: 23.2222, longitude: 44.333 } ] }, { date: new Date(1483311600000), geoStamps: [ { dateTime: new Date(1492019739661), latitude: 23.2222, longitude: 44.333 }, { dateTime: new Date(1492019739661), latitude: 23.2222, longitude: 44.333 }, { dateTime: new Date(1492019739661), latitude: 23.2222, longitude: 44.333 } ] } ]})'

The latitudes and longitudes you see in the error are ones I'm trying to insert.

Any ideas on how to accomplish this?

Answer 1

Turns out I wasn't actually pushing to an array, this:

final UpdateOperations<Tracker> trackerUpdate = datastore.createUpdateOperations(Tracker.class).push("days.geoStamps", newGeoStamps);

should've been:

final UpdateOperations<Tracker> trackerUpdate = datastore.createUpdateOperations(Tracker.class)
                .push("days.$.geoStamps", newGeoStamps);

Hope this might help someone in the future!