I'm having trouble setting up my daily files. `spdlog::sinks::daily_file_sink_mt`

[Mq-b]

Here's my config code:

inline void setupLogging() {
    if(std::filesystem::exists("Log")){
        std::filesystem::create_directory("Log");
    }
    auto file_sink = std::make_shared<spdlog::sinks::daily_file_sink_mt>("Log/daily.log", 0, 0);
    file_sink->set_level(spdlog::level::debug);
    file_sink->set_pattern("[%Y-%m-%d %H:%M:%S] [thread %t] [%oms] [%l] %v");

    auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
    console_sink->set_level(spdlog::level::debug);
    console_sink->set_pattern("%^[%Y-%m-%d %H:%M:%S] [thread %t] [%oms] [%l] %v%$");

    auto logger = std::make_shared<spdlog::logger>("multi_sink", spdlog::sinks_init_list{ file_sink, console_sink });
    spdlog::register_logger(logger);

    spdlog::set_default_logger(logger);
    spdlog::flush_on(spdlog::level::debug);
}

It works fine, new files are created based on the date, but the problem is I can't set the file name I want.

For example, this code creates a file like daily_2025-03-05.log.

And I only want the date, not the 'daily_' in front of it, I don't know how to get rid of it. Can you help me? Thank you very much.

[tt4g]

You can replace FileNameCalc template parameter to change log filename.

spdlog/include/spdlog/sinks/daily_file_sink.h

Line 68 in faa0a7a

template <typename Mutex, typename FileNameCalc = daily_filename_calculator>

Default implementation:

spdlog/include/spdlog/sinks/daily_file_sink.h

Lines 26 to 38 in faa0a7a

	/*
	* Generator of daily log file names in format basename.YYYY-MM-DD.ext
	*/
	struct daily_filename_calculator {
	// Create filename for the form basename.YYYY-MM-DD
	static filename_t calc_filename(const filename_t &filename, const tm &now_tm) {
	filename_t basename, ext;
	std::tie(basename, ext) = details::file_helper::split_by_extension(filename);
	return fmt_lib::format(SPDLOG_FMT_STRING(SPDLOG_FILENAME_T("{}_{:04d}-{:02d}-{:02d}{}")),
	basename, now_tm.tm_year + 1900, now_tm.tm_mon + 1, now_tm.tm_mday,
	ext);
	}
	};

[Mq-b]

Thank you very much for your reply, I'll give it a try and I'd be very grateful if you could provide a clearer example.

[tt4g]

Example (I have not checked it works):

 struct daily_only_calculator { 
     static spdlog::filename_t calc_filename(const spdlog::filename_t &filename, const tm &now_tm) { 
         spdlog::filename_t basename_unused, ext; 
         std::tie(basename_unused, ext) = spdlog::details::file_helper::split_by_extension(filename); 
         return spdlog::fmt_lib::format(SPDLOG_FMT_STRING(SPDLOG_FILENAME_T("{:04d}-{:02d}-{:02d}{}")), 
                                now_tm.tm_year + 1900, now_tm.tm_mon + 1, now_tm.tm_mday, 
                                ext); 
     } 
 };

using daily_only_format_sink_mt = spdlog::daily_file_sink<std::mutex, daily_only_calculator>;

auto sink = std::make_shared<daily_only_format_sink_mt>("Log/_.log", 0, 0);

Another way, using spdlog::daily_file_format_sink_mt:

auto sink = std::make_shared<spdlog::daily_file_format_sink_mt>("Log/%Y-%m-%d.log", 0, 0);

See daily_file_format_sink:

spdlog/include/spdlog/sinks/daily_file_sink.h

Lines 40 to 59 in faa0a7a

	/*
	* Generator of daily log file names with strftime format.
	* Usages:
	* auto sink =
	* std::make_shared<spdlog::sinks::daily_file_format_sink_mt>("myapp-%Y-%m-%d:%H:%M:%S.log", hour,
	* minute);" auto logger = spdlog::daily_logger_format_mt("loggername, "myapp-%Y-%m-%d:%X.log",
	* hour, minute)"
	*
	*/
	struct daily_filename_format_calculator {
	static filename_t calc_filename(const filename_t &file_path, const tm &now_tm) {
	#if defined(_WIN32) && defined(SPDLOG_WCHAR_FILENAMES)
	std::wstringstream stream;
	#else
	std::stringstream stream;
	#endif
	stream << std::put_time(&now_tm, file_path.c_str());
	return stream.str();
	}
	};

spdlog/include/spdlog/sinks/daily_file_sink.h

Lines 196 to 198 in faa0a7a

	using daily_file_format_sink_mt = daily_file_sink<std::mutex, daily_filename_format_calculator>;
	using daily_file_format_sink_st =
	daily_file_sink<details::null_mutex, daily_filename_format_calculator>;

[Mq-b]

@tt4g Thank you very much for your reply and help, I will test it in the company project when I go to work tomorrow.