Review test mysql

mysql-review.cpp

#include <iostream>
#include <boost/asio.hpp>
#include <boost/mysql.hpp>

using namespace boost;


struct printer
{
    template<typename T>
    auto & operator()(const T & t)
    {
        return std::cout << t;
    }

    template<typename Clock, typename Duration>
    auto & operator()(const std::chrono::time_point<Clock, Duration> & t)
    {
        return std::cout << "<timestamp>";
    }

    template<typename Clock, typename Duration>
    auto & operator()(const std::chrono::duration<Clock, Duration> & t)
    {
        return std::cout << "<duration>";
    }
};

using executor_type = asio::use_awaitable_t<>::executor_with_default<asio::any_io_executor>;

template<typename Stream>
asio::awaitable<void> print_result(mysql::resultset<Stream> & res)
{
    for (const boost::mysql::row& row : co_await res.async_read_all())
    {
        std::cout << "Row: ";
        for (const auto & col : row.values())
            visit(printer{}, col.to_variant()) << ", ";
        std::cout << std::endl;
    }
}

asio::awaitable<void> test()
{
    using socket_type = asio::ip::tcp::socket::rebind_executor<executor_type>::other;
    using resolv_type = asio::ip::tcp::resolver::rebind_executor<executor_type>::other;
    using mysql_conn = mysql::connection<socket_type>;
    auto exec = co_await asio::this_coro::executor;

    mysql_conn conn(exec);
    resolv_type  res(exec);

    auto itr = co_await res.async_resolve("localhost", "mysql");

    co_await conn.async_connect(*itr.begin(), mysql::connection_params("root", "mypass", "review"));

    // language=mysql
    auto req = co_await conn.async_query(R"(select 'Hello World!')");
    co_await print_result(req);


    // language=mysql
    req = co_await conn.async_query(R"(create database if not exists review;)");
    co_await print_result(req);

    // language=mysql
    req = co_await conn.async_query(R"(create table if not exists users(
                                            user_id INT AUTO_INCREMENT PRIMARY KEY,
                                            username VARCHAR(40),
                                            password VARCHAR(255)))");
    co_await print_result(req);

    auto prep = co_await conn.async_prepare_statement(R"(INSERT INTO users(username, password) VALUES (?, ?), (?, ?))");
    req = co_await prep.async_execute(mysql::make_values("admin", "admin", "root", "password"));
    co_await print_result(req);

    req = co_await conn.async_query(R"(select * from users)");
    co_await print_result(req);


    req = co_await conn.async_query(R"(drop table users)");
    co_await print_result(req);


    co_await conn.async_quit();
    co_return ;
}

int main()
{
    // docker run --name mariadbtest -e MYSQL_ROOT_PASSWORD=mypass -p 3306:3306 -d mariadb
    asio::io_context ctx;
    asio::co_spawn(ctx, test(), [](auto e) {if (e) std::rethrow_exception(e);});

    asio::steady_timer tim{ctx};

    ctx.run();

    return 0;
}