Mongodb java find document and filter an array field (delete array data that don't match a condition)

Question

I try to request a Collection but impossible to filter the embedded array. I would like to get every Documents in the Collection that match {"players.nick" : nick } and filter the 'players' array to get only the searched player inside.

Here is the intial Document :

{"_id":2000,"type":3,"prizepool":6520.5,"name":"XXX","start":1515701700,"end":1515719580,"buyin":2.25,"rake":0.5,"prize":0,"bounty":2.25,"players":[{"nick":"player1","rank":1,"cash":660.85,"kill":468.64,"ticket":0,"reentry":0},{"nick":"player2","rank":2,"cash":430.35,"kill":101.31,"ticket":0,"reentry":0},{"nick":"player3","rank":3,"cash":312.98,"kill":72.26,"ticket":0,"reentry":0},{"nick":"player4","rank":4,"cash":237.99,"kill":27.15,"ticket":0,"reentry":1}]}

And after requesting I would like to retrieve :

{"_id":2000,"type":3,"prizepool":6520.5,"name":"XXX","start":1515701700,"end":1515719580,"buyin":2.25,"rake":0.5,"prize":0,"bounty":2.25,"players":[{"nick":"player1","rank":1,"cash":660.85,"kill":468.64,"ticket":0,"reentry":0}}

Does anyone know how to do that in a java way ?

Thanks !

s7vr · Accepted Answer · 2018-01-16 15:01:10Z

4

You can use below aggregation pipeline in java.

MongoClient mc = new MongoClient();
MongoDatabase db = mc.getDatabase(db);
MongoCollection col = db.getCollection(col);

For single match you can use $elemMatch projection

col.find().projection(Projections.fields(Projections.include("_id","type", "prizepool","name","start","end","buyin","rake","prize","bounty"),
                Projections.elemMatch("players", Filters.eq("nick", "player1"))));

For both single & multiple matches

Bson filter = new Document("players", Document.parse("{\n" +
            "            $filter: {\n" +
            "               input: \"$players\",\n" +
            "               as: \"player\",\n" +
            "               cond: { $eq: [ \"$$player.nick\", \"player1\" ] }\n" +
            "            }\n" +
            "         }"));
Bson addFields = new Document("$addFields", filter);
col.aggregate(Arrays.asList(addFields));

answered Jan 16, 2018 at 15:01

s7vr

76.2k12 gold badges118 silver badges135 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

David B Over a year ago

Thanks a lot ! It works perfectly... I was working on it the entire day... You rock !

Petter Friberg Over a year ago

@DavidB if this answer work for you "accept" it, that's the way to thank on SO and it also the correct indication for other users that you solved it using this. (never add solved to title of question)

Collectives™ on Stack Overflow

Mongodb java find document and filter an array field (delete array data that don't match a condition)

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related