boost log format single attribute with logging::init_from_stream - c++

Question

When I set up format params in code, to format date time output I can use something like this
logging::formatter simpleFormat(expr::format("%1% %2%") %
expr::format_date_time<boost::posix_time::ptime>("TimeStamp", "%H:%M:%S") %
expr::smessage
);
But when I initialize logger with a config file, I can specify format only in attributes position notation, not their format details.
so, this line in a boost log config file
Format="[%TimeStamp%]: %Message%"
produces output:
[2015-Feb-06 09:32:27.401496]: blah blah blah
I want to reduce timestamp to something like this
[06.02.2015 09:32:27]
How can it be described in boost log config file, ot it cant be done at all?

Answer 1

Preamble
My answer is valid for boost 1.55 (haven't tested with latest one). And it was only tested with MSVC 2013 compiler.
Answer
Looks like you need custom formatter_factory for TimeStamp attribute to be able to specify it's format. This works for me:
#include <fstream>
#include "boost/shared_ptr.hpp"
#include "boost/log/trivial.hpp"
#include "boost/log/expressions.hpp"
#include "boost/log/utility/setup.hpp"
#include "boost/log/support/date_time.hpp"
class timestamp_formatter_factory :
public boost::log::basic_formatter_factory<char, boost::posix_time::ptime>
{
public:
formatter_type create_formatter(boost::log::attribute_name const& name, args_map const& args)
{
args_map::const_iterator it = args.find("format");
if (it != args.end())
return boost::log::expressions::stream << boost::log::expressions::format_date_time<boost::posix_time::ptime>(boost::log::expressions::attr<boost::posix_time::ptime>(name), it->second);
else
return boost::log::expressions::stream << boost::log::expressions::attr<boost::posix_time::ptime>(name);
}
};
int main()
{
// Initializing logging
boost::log::register_formatter_factory("TimeStamp", boost::make_shared<timestamp_formatter_factory>());
boost::log::add_common_attributes();
std::ifstream file("settings.ini");
boost::log::init_from_stream(file);
// Testing
BOOST_LOG_TRIVIAL(info) << "Test";
return 0;
}
And now it your settings file you can specify format argument for TimeStamp attribute. Like this:
[Sinks.ConsoleOut]
Destination=Console
AutoFlush=true
Format="[%TimeStamp(format=\"%Y.%m.%d %H:%M:%S\")%]: %Message%"

Answer 2

You should be able to use set_formatter as documented here
sink->set_formatter
(
expr::stream << expr::format_date_time< boost::posix_time::ptime >("TimeStamp", "%Y-%m-%d %H:%M:%S")
);