Spring - mongodb - aggregation - The 'cursor' option is required

Question

Executing the following aggregation pipeline:

public void getMostLikedItems () {
        UnwindOperation unwind = Aggregation.unwind("favoriteItems");
        GroupOperation group = Aggregation.group("favoriteItems").count().as("likes");
        SortOperation sort = Aggregation.sort(Sort.Direction.DESC, "likes");

        Aggregation aggregation = newAggregation(unwind, group, sort);
        DBObject result = mongoTemplate.aggregate(aggregation, "users", LikedItem.class).getRawResults();
}

throws the following exception:

com.mongodb.MongoCommandException: Command failed with error 9: 'The 'cursor' option is required, except for aggregate with the explain argument' on server localhost:27017. The full response is { "ok" : 0.0, "errmsg" : "The 'cursor' option is required, except for aggregate with the explain argument", "code" : 9, "codeName" : "FailedToParse" }

I don't understand what is meant by cursor option here. Where should this option be configured?

EDIT Here is a sample user document

{
  "_id": "5a6df13552f42a34dcca9aa6",
  "username": "user1",
  "password": "$2a$10$p0OXq5PPa41j1e4iPcGZHuWjoKJ983sieS/ovFI.cVX5Whwj21WYi",
  "favoriteItems": [
    {
      "_id": "5a0c6b2dfd3eb67969316d6d",
      "name": "item1",
      "city": "Rabat"
    },
    {
      "_id": "5a0c680afd3eb67969316d0b",
      "name": "item2",
      "city": "Rabat"
    }
  ]
}

Answer 1

From the docs.

MongoDB 3.4 deprecates the use of aggregate command without the cursor option, unless the pipeline includes the explain option. When returning aggregation results inline using the aggregate command, specify the cursor option using the default batch size cursor: {} or specify the batch size in the cursor option cursor: { batchSize: }.

You can pass batchSize with AggregationOptions in Spring Mongo 2.x version

Aggregation aggregation = newAggregation(unwind, group).withOptions(newAggregationOptions().cursorBatchSize(100).build());

With default batch size

Aggregation aggregation = newAggregation(unwind, group).withOptions(newAggregationOptions().cursor(new Document()).build());