React::Mongo::Connection mongo("mongodb.example.org", [](React::Mongo::Connection *connection, const char *error) {
    // if no error occured, we will receive a null pointer
    if (!error) std::cout << "Connected successfully" << std::endl;

    // otherwise, we will get a description of what exactly went wrong
    else std::cout << "Connection error: " << error << std::endl;
});

/**
 *  The mongo object will be created immediately, even though the connection
 *  might not have been established. It is safe, however, to immediately run
 *  the next command on the object. They will be executed after a connection
 *  was established. Should the library fail to connect, all registered calls
 *  will receive an error.
 */

// build a query to find a specific document
Variant::Value query;
query["_id"] = "documentid";

// retrieve the document
mongo.query("database.collection", std::move(query)).onSuccess([](Variant::Value&& result) {
    // since we search for an exact id, we will get a maximum of one result
    // however, this result will always be an array
    if (result.size() == 0)
    {
        std::cout << "Could not find any document with that ID" << std::endl;
        return;
    }

    // assume that the document has a string field named 'firstname'
    std::string firstname = result[0]["firstname"];
}).onError([](const char *error) {
    std::cout << "Something went wrong querying: " << error << std::endl;
});

Variant::Value document;
document["name"] = "Example User";
document["email"] = "[email protected]";
document["address"]["city"] = "Gotham City";
document["address"]["phone"] = "555-BATMAN";

mongo.insert("database.collection", std::move(document)).onSuccess([]() {
    std::cout << "Document inserted" << std::endl;
}).onError([](const char *error) {
    std::cout << "Could not insert document: " << error << std::endl;
});