// Copyright 2009-present MongoDB, 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 #include #include #include #include #include #include #include #include using bsoncxx::builder::basic::kvp; using bsoncxx::builder::basic::make_document; int EXAMPLES_CDECL main() { // The mongocxx::instance constructor and destructor initialize and shut down the driver, // respectively. Therefore, a mongocxx::instance must be created before using the driver and // must remain alive for as long as the driver is in use. mongocxx::instance inst{}; mongocxx::client conn{mongocxx::uri{}}; auto coll = conn["test"]["query_projection"]; coll.drop(); // Insert a test document auto result = coll.insert_one(make_document(kvp("user info", make_document(kvp("user name", "Joe"))))); std::cout << "Inserted " << result->inserted_id().get_oid().value.to_string() << std::endl; // Create the find options with the projection mongocxx::options::find opts{}; opts.projection(make_document(kvp("_id", 1))); // Execute find with options auto cursor = coll.find(make_document(kvp("user info.user name", "Joe")), opts); for (auto&& doc : cursor) { std::cout << bsoncxx::to_json(doc) << std::endl; } return EXIT_SUCCESS; }