Timestamp format in JSON logging not conforming to timestamp pattern

[persona94]

I used the code from the JSON logging page

#include "quill/Backend.h"
#include "quill/Frontend.h"
#include "quill/LogMacros.h"
#include "quill/Logger.h"
#include "quill/sinks/JsonConsoleSink.h"
#include <string>

int main()
{
    quill::BackendOptions backend_options;
    quill::Backend::start(backend_options);

    auto json_sink = quill::Frontend::create_or_get_sink<quill::JsonConsoleSink>("json_sink_1");

    // When logging json, it is ideal to set the logging pattern to empty to avoid unnecessary message formatting.
    quill::Logger* logger = quill::Frontend::create_or_get_logger(
      "json_logger", std::move(json_sink), quill::PatternFormatterOptions { "", "%H:%M:%S.%Qns", quill::Timezone::GmtTime });

    int var_a = 123;
    std::string var_b = "test";

    // Log via the convenient LOGJ_ macros
    LOGJ_INFO(logger, "A json message", var_a, var_b);

    // Or manually specify the desired names of each variable
    LOG_INFO(logger, "A json message with {var_1} and {var_2}", var_a, var_b);
}

The output is

{"timestamp":"1728071935315527792","file_name":"main.cpp","line":"23","thread_id":"1412467","logger":"json_logger","log_level":"INFO","message":"A json message {var_a}, {var_b}","var_a":"123","var_b":"test"}
{"timestamp":"1728071935315569792","file_name":"main.cpp","line":"26","thread_id":"1412467","logger":"json_logger","log_level":"INFO","message":"A json message with {var_1} and {var_2}","var_1":"123","var_2":"test"}

Why are the timestamps in epoch and not human readable format?

[odygrd]

Currently, you can have both a normal output and a JSON output simultaneously. However, the JsonSink is performing its own formatting and does not follow the PatternFormatter used for regular files.

The JsonSink handles formatting here:

• JsonFileSink
• JsonConsoleSink

I recommend creating your own JsonSink type by deriving from these classes and implementing your own write_log function with the desired format. You can refer to this example for guidance:

• User-Defined Sink Example

I will look into how this can be improved in future versions.

[persona94]

Ah gotcha. Thank you for the very prompt response! I'll look into a user-defined sink because I need to embed some thread specific data anyway