Spring data mongodb - aggregation framework integration

Question

I started to use MongoDB database in my application and for data access I have chosen Spring Data for MongoDB.

I skimmed API reference and documentation and I can see that there is map-reduce integration but what about aggregation framework? I can see that it supports group by operation, which would indicate that it supports $group operator judging from this: http://docs.mongodb.org/manual/reference/sql-aggregation-comparison/, but what about other operators, are that not supported for now?

I am asking this question because I wanted to know what kind of integration with MongoDB Sping Data provides so I know what to expect, so to speak.

Answer 1

Spring Data 1.3.0.RC1 is available and it does support the aggregation framework.

For example: The shell aggregation comand:

db.eft_transactions.aggregate(
    {$match:
        {
            service:"EFT",
            source:"MARKUP",
        }
    },
    {$group:
        {
            _id:"$card_acceptor_id",
            tran_count:{$sum:1},
            amount_sum:{$sum:"$amount"}
        }
    }
)

is run like this from java:

    AggregationOperation match = Aggregation.match(Criteria.where("service").is("EFT").and("source").is("MARKUP"));
    AggregationOperation group = Aggregation.group("card_acceptor").and("amount_sum").sum("amount").and("tran_count").count();
    Aggregation aggregation = newAggregation(match, group);
    AggregationResults<StoreSummary> result = this.mongoTemplate.aggregate(aggregation, "eft_transactions", StoreSummary.class);

The documentation is here

NOTE: We recently had to switch to using the BUILD-SNAPSHOT build of version 1.3.0. This change necessitated the change to 2 of the above lines which have changed to:

AggregationOperation group = Aggregation.group("card_acceptor").sum("amount").as("amount_sum").count().as("tran_count");
Aggregation aggregation = Aggregation.newAggregation(match, group);

Answer 2

The Spring Data MongoOperations.group() method is mapped to db.collection.group() MongoDB command and not the $group aggregation function. Currently there is no support in Spring Data MongoDB for aggregation framework. Map reduce, as you have mentioned, is supported though

Answer 3

 Aggregation aggregation = newAggregation(
        match(Criteria.where("salesyear").is(year)),
        group("brand","salesyear").sum("numberOfCars").as("total"),
        sort(Sort.Direction.ASC, previousOperation(), "brand")    
      );