Spring mongo repository slice

Question

I am using spring-sata-mongodb 1.8.2 with MongoRepository and I am trying to use the mongo $slice option to limit a list size when query, but I can\'t find this option in th

Answer 1

Providing an abstraction for the $slice operator in Query is still an open issue. Please vote for DATAMONGO-1230 and help us prioritize.

For now you still can fall back to using BasicQuery.

String qry = "{ \"_id\" : \"record-id\"}";
String fields = "{\"fields\": { \"$slice\": 2} }";

BasicQuery query = new BasicQuery(qry, fields);

Answer 2

Use slice functionality as provided in Java Mongo driver using projection as in below code.

For Example:

List<Entity> list = new ArrayList<Entity>();
        // Return the last 10 weeks data only
FindIterable<Document> list = db.getDBCollection("COLLECTION").find()
                .projection(Projections.fields(Projections.slice("count", -10)));
MongoCursor<Document> doc = list.iterator();
while(doc.hasNext()){
    list.add(new Gson().fromJson(doc.next().toJson(), Entity.class));
}

The above query will fetch all documents of type Entity class and the "field" list of each Entity class document will have only last 10 records.

Answer 3

I found in unit test file (DATAMONGO-1457) way to use slice. Some thing like this.

newAggregation(
    UserWithLikes.class, 
    match(new Criteria()),
    project().and("likes").slice(2)
);