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//
// Copyright (c) 2019-2023 Ruben Perez Hidalgo (rubenperez038 at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
//[example_async_callbacks
#include <boost/mysql/connection.hpp>
#include <boost/mysql/diagnostics.hpp>
#include <boost/mysql/error_code.hpp>
#include <boost/mysql/error_with_diagnostics.hpp>
#include <boost/mysql/handshake_params.hpp>
#include <boost/mysql/results.hpp>
#include <boost/mysql/row_view.hpp>
#include <boost/mysql/statement.hpp>
#include <boost/mysql/tcp_ssl.hpp>
#include <boost/mysql/throw_on_error.hpp>
#include <boost/asio/io_context.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/ssl/context.hpp>
#include <iostream>
using boost::mysql::error_code;
void print_employee(boost::mysql::row_view employee)
{
std::cout << "Employee '" << employee.at(0) << " " // first_name (string)
<< employee.at(1) << "' earns " // last_name (string)
<< employee.at(2) << " dollars yearly\n"; // salary (double)
}
class application
{
boost::asio::ip::tcp::resolver::results_type eps; // Physical endpoint(s) to connect to
boost::mysql::handshake_params conn_params; // MySQL credentials and other connection config
boost::asio::io_context ctx; // boost::asio context
boost::asio::ip::tcp::resolver resolver; // To perform hostname resolution
boost::asio::ssl::context ssl_ctx; // MySQL 8+ default settings require SSL
boost::mysql::tcp_ssl_connection conn; // Represents the connection to the MySQL server
boost::mysql::statement stmt; // A prepared statement
boost::mysql::results result; // A result from a query
boost::mysql::diagnostics diag; // Will be populated with info about server errors
const char* company_id; // The ID of the company whose employees we want to list. Untrusted.
public:
application(const char* username, const char* password, const char* company_id)
: conn_params(username, password, "boost_mysql_examples"),
resolver(ctx.get_executor()),
ssl_ctx(boost::asio::ssl::context::tls_client),
conn(ctx, ssl_ctx),
company_id(company_id)
{
}
void start(const char* hostname) { resolve_hostname(hostname); }
void resolve_hostname(const char* hostname)
{
resolver.async_resolve(
hostname,
boost::mysql::default_port_string,
[this](error_code err, boost::asio::ip::tcp::resolver::results_type results) {
boost::mysql::throw_on_error(err);
eps = std::move(results);
connect();
}
);
}
void connect()
{
conn.async_connect(*eps.begin(), conn_params, diag, [this](error_code err) {
boost::mysql::throw_on_error(err, diag);
prepare_statement();
});
}
void prepare_statement()
{
// We will be using company_id, which is untrusted user input, so we will use a prepared
// statement.
conn.async_prepare_statement(
"SELECT first_name, last_name, salary FROM employee WHERE company_id = ?",
diag,
[this](error_code err, boost::mysql::statement temp_stmt) {
boost::mysql::throw_on_error(err, diag);
stmt = temp_stmt;
query_employees();
}
);
}
void query_employees()
{
conn.async_execute(stmt.bind(company_id), result, diag, [this](error_code err) {
boost::mysql::throw_on_error(err, diag);
for (boost::mysql::row_view employee : result.rows())
{
print_employee(employee);
}
close();
});
}
void close()
{
// Notify the MySQL server we want to quit and then close the socket
conn.async_close(diag, [this](error_code err) { boost::mysql::throw_on_error(err, diag); });
}
void run() { ctx.run(); }
};
void main_impl(int argc, char** argv)
{
if (argc != 4 && argc != 5)
{
std::cerr << "Usage: " << argv[0] << " <username> <password> <server-hostname> [company-id]\n";
exit(1);
}
// The company_id whose employees we will be listing. This
// is user-supplied input, and should be treated as untrusted.
const char* company_id = argc == 5 ? argv[4] : "HGS";
application app(argv[1], argv[2], company_id);
app.start(argv[3]); // starts the async chain
app.run(); // run the asio::io_context until the async chain finishes
}
int main(int argc, char** argv)
{
try
{
main_impl(argc, argv);
}
catch (const boost::mysql::error_with_diagnostics& err)
{
// Some errors include additional diagnostics, like server-provided error messages.
// Security note: diagnostics::server_message may contain user-supplied values (e.g. the
// field value that caused the error) and is encoded using to the connection's encoding
// (UTF-8 by default). Treat is as untrusted input.
std::cerr << "Error: " << err.what() << '\n'
<< "Server diagnostics: " << err.get_diagnostics().server_message() << std::endl;
return 1;
}
catch (const std::exception& err)
{
std::cerr << "Error: " << err.what() << std::endl;
return 1;
}
}
//]
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