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// 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 <cstdlib>
#include <iostream>
#include <string>
#include <bsoncxx/builder/basic/document.hpp>
#include <bsoncxx/builder/basic/kvp.hpp>
#include <bsoncxx/json.hpp>
#include <mongocxx/client.hpp>
#include <mongocxx/client_session.hpp>
#include <mongocxx/collection.hpp>
#include <mongocxx/exception/exception.hpp>
#include <mongocxx/instance.hpp>
#include <mongocxx/options/insert.hpp>
#include <mongocxx/options/transaction.hpp>
#include <mongocxx/read_concern.hpp>
#include <mongocxx/read_preference.hpp>
#include <mongocxx/uri.hpp>
#include <mongocxx/write_concern.hpp>
#include <examples/macros.hh>
using bsoncxx::builder::basic::kvp;
using bsoncxx::builder::basic::make_document;
using namespace mongocxx;
//
// This example shows how to use the client_session::with_transaction helper to
// conveniently run a custom callback inside of a transaction.
//
int EXAMPLES_CDECL main() {
if (const char* const topology_env = std::getenv("MONGOCXX_TEST_TOPOLOGY")) {
const auto topology = std::string(topology_env);
if (topology != "replica") {
std::cerr << "Skipping: with_transaction example requires a replica set" << std::endl;
return 0;
}
}
// Start Transactions withTxn API Example 1
// 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{};
// For a replica set, include the replica set name and a seedlist of the members in the URI
// string; e.g.
// uriString =
// 'mongodb://mongodb0.example.com:27017,mongodb1.example.com:27017/?replicaSet=myRepl'
// For a sharded cluster, connect to the mongos instances; e.g.
// uriString = 'mongodb://mongos0.example.com:27017,mongos1.example.com:27017/'
mongocxx::client client{mongocxx::uri{"mongodb://localhost/?replicaSet=repl0"}};
// Prepare to set majority write explicitly. Note: on Atlas deployments this won't always be
// needed. The suggested Atlas connection string includes majority write concern by default.
write_concern wc_majority{};
wc_majority.acknowledge_level(write_concern::level::k_majority);
// Prereq: Create collections.
auto foo = client["mydb1"]["foo"];
auto bar = client["mydb2"]["bar"];
try {
options::insert opts;
opts.write_concern(wc_majority);
foo.insert_one(make_document(kvp("abc", 0)), opts);
bar.insert_one(make_document(kvp("xyz", 0)), opts);
} catch (const mongocxx::exception& e) {
std::cout << "An exception occurred while inserting: " << e.what() << std::endl;
return EXIT_FAILURE;
}
// Step 1: Define the callback that specifies the sequence of operations to perform inside the
// transactions.
client_session::with_transaction_cb callback = [&](client_session* session) {
// Important:: You must pass the session to the operations.
foo.insert_one(*session, make_document(kvp("abc", 1)));
bar.insert_one(*session, make_document(kvp("xyz", 999)));
};
// Step 2: Start a client session
auto session = client.start_session();
// Step 3: Use with_transaction to start a transaction, execute the callback,
// and commit (or abort on error).
try {
options::transaction opts;
opts.write_concern(wc_majority);
session.with_transaction(callback, opts);
} catch (const mongocxx::exception& e) {
std::cout << "An exception occurred: " << e.what() << std::endl;
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
// End Transactions withTxn API Example 1
}
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