Spring Data MongoDB - Aggregations
This project contains usage samples for using MongoDB Aggregations showing both the programmatic and declarative approach for integrating an Aggregation Pipeline into the repository lay.
Programmatic
The programmatic approach uses a custom repository implementation along with the Aggregation Framework.
class OrderRepositoryImpl implements OrderRepositoryCustom {
private MongoOperations operations;
// ...
@Override
public Invoice getInvoiceFor(Order order) {
AggregationResults<Invoice> results = operations.aggregate(newAggregation(Order.class,
match(where("id").is(order.getId())),
unwind("items"),
project("id", "customerId", "items")
.andExpression("'$items.price' * '$items.quantity'").as("lineTotal"),
group("id")
.sum("lineTotal").as("netAmount")
.addToSet("items").as("items"),
project("id", "items", "netAmount")
.and("orderId").previousOperation()
.andExpression("netAmount * [0]", taxRate).as("taxAmount")
.andExpression("netAmount * (1 + [0])", taxRate).as("totalAmount")
), Invoice.class);
return results.getUniqueMappedResult();
}
}
Declarative
The declarative approach allows to define an Aggregation Pipeline via the @Aggregation annotation.
public interface OrderRepository extends CrudRepository<Order, String>, OrderRepositoryCustom {
@Aggregation("{ $group : { _id : $customerId, total : { $sum : 1 } } }")
List<OrdersPerCustomer> totalOrdersPerCustomer(Sort sort);
@Aggregation(pipeline = { "{ $match : { customerId : ?0 } }", "{ $count : total }" })
Long totalOrdersForCustomer(String customerId);
}