Streaming the result of an aggregate operation using spring-data-mongodb

Question

I am using spring-data-mongodb and I want to use a cursor for an aggregate operation.

MongoTemplate.stream() gets a Query, so I tried creating the Aggregati

Answer 1

For those who are still trying to find the answer to this:

From spring-data-mongo version 2.0.0.M4 onwards (AFAIK) MongoTemplate got an aggregateStream method.

So you can do the following:

 AggregationOptions aggregationOptions = Aggregation.newAggregationOptions()
        // this is very important: if you do not set the batch size, you'll get all the objects at once and you might run out of memory if the returning data set is too large
        .cursorBatchSize(mongoCursorBatchSize)
        .build();

    data = mongoTemplate.aggregateStream(Aggregation.newAggregation(
            Aggregation.group("person_id").count().as("count")).withOptions(aggregationOptions), collectionName, YourClazz.class);