How to search through nested array and retreive only matched elements with mongo and springdata

Question

I'm looking to search into my collection and retreive only element who matched Criteria.

Here is my collection :

{
"_id" : "id",
"name" : "test",
"groupUsers" : [ 
    {
        "name" : "blabla",
        "toys" : [ 
            {
                "createdAt" : ISODate("2019-10-30T12:59:41.409Z"),
            },
            {
                "createdAt" : ISODate("2019-11-30T12:59:10.409Z"),
            },
            {
                "createdAt" : ISODate("2019-12-30T12:59:12.409Z"),
            }
        ],
        "createdAt" : ISODate("2019-10-30T12:33:39.036Z")
    },
    {
        "name" : "blabla2",
        "toys" : [ 
            {
                "createdAt" : ISODate("2019-10-32T12:59:41.409Z"),
            },
            {
                "createdAt" : ISODate("2019-11-30T12:59:56.409Z"),
            },
            {
                "createdAt" : ISODate("2019-12-30T12:59:15.409Z"),
            }
        ],
        "createdAt" : ISODate("2019-10-32T12:33:39.036Z")
    }
],
}

I want to retreive the whole collection but it depends when the user was added to the group for example, user blabla2 (in the example above) will only get the whole group but with only the two last toys of the first user in the response.

Anyway, I guess it's something really basic but I don't know why I can't figure it out.

What I'm Doing

I'm doing a first query to get the current user and get when he was added in the group (notice that the date gets converted into java Date Util here).

Aggregation groupAgg = newAggregation(match(Criteria.where("_id").is(groupId).and("groupUsers.userId").is(userId)));
GroupUser groupUser = mongoTemplate.aggregate(groupAgg, Group.class, GroupUser.class).getUniqueMappedResult();

In a second query, I want to get the whole document but only with the Criteria that I define before.

MatchOperation matchedGroup = match(new Criteria("_id").is(groupId));
MatchOperation matchedToys = match(
    new Criteria("groupUsers.toys.createdAt").gte(groupUser.getCreatedAt()));

Aggregation aggregation = newAggregation(matchedGroup, matchedToys);

AggregationResults<Group> result = mongoTemplate.aggregate(aggregation, Group.class, Group.class);
Group group = result.getUniqueMappedResult();

This query doesn't work, and I'm looking to something like even if there is no match (for example, none toys has been created yet), it still return the group basic response and not null. Maybe I need to unwind the nested array ? Any help is appreciate. I'm using spring data.

score 0 · Answer 1 · answered Oct 30 '19 at 14:26

Try this query

db.testers.aggregate([
    {
        $addFields:{
            "groupUsers":{
                $map:{
                    "input":"$groupUsers",
                    "as":"doc",
                    "in":{
                        $mergeObjects:[
                            "$$doc",
                            {
                                "toys":{
                                    $filter:{
                                        "input":"$$doc. toys",
                                        "as":"sn",
                                        "cond": {
                                        "$and": [
                                            { "$gte": [ "$$sn.createdAt", ISODate('2015-06-17T10:03:46.000Z') ] },
                                        ]
                                    }

                                }
                            }
                            }
                        ]
                    }
                }
            }
        }
    }
]).pretty()

It's not working, and I'm looking for a spring data answer but thank you for your help — cfrapper, Oct 30 '19 at 14:45
The way spring boot works with mongo, https://docs.spring.io/spring-data/mongodb/docs/current/reference/html/#reference — cfrapper, Oct 30 '19 at 14:55

How to search through nested array and retreive only matched elements with mongo and springdata

1 Answers1