Aggregation Framework Example

aggregation.cpp

/*    Copyright 2014 10gen Inc.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

#include <iostream>
#include <memory>

#include "mongo/client/dbclient.h"

using namespace mongo;

int main(int argc, char* argv[]) {

    const char *port = "27017";
    if ( argc != 1 ) {
        if ( argc != 3 ) {
            std::cout << "need to pass port as second param" << std::endl;
            return EXIT_FAILURE;
        }
        port = argv[ 2 ];
    }

    Status status = client::initialize();

    if (status.isOK()) {
        DBClientConnection conn;
        conn.connect(std::string("localhost:").append(port));
        conn.dropCollection("test.test");

        conn.insert("test.test", BSON("x" << 0));
        conn.insert("test.test", BSON("x" << 1));
        conn.insert("test.test", BSON("x" << 1));
        conn.insert("test.test", BSON("x" << 2));
        conn.insert("test.test", BSON("x" << 2));
        conn.insert("test.test", BSON("x" << 2));

        std::auto_ptr<DBClientCursor> cursor = conn.aggregate("test.test",
            BSON_ARRAY(
                BSON("$match" << BSON("x" << GT << 0)) <<
                BSON("$group" << BSON("_id" << "$x" << "count" << BSON("$sum" << 1)))
            )
        );

        std::cout << "------- AGGREGATION -------" << std::endl;
        while (cursor->more()) {
            std::cout << cursor->next() << std::endl;
        }
    }
}