How to Handle JSON Dates and Times in Go

Serde

2026-04-17T12:05:42+00:00

Handle JSON dates in Go tar archives by using Header time fields and setting Format to PAX or GNU for precision.

Use the time.Time fields in archive/tar.Header and specify FormatPAX to preserve sub-second precision or FormatGNU for full compatibility. The default FormatUnknown rounds ModTime to the nearest second and ignores AccessTime and ChangeTime.

hdr := &tar.Header{
    Name:     "file.txt",
    Size:     1024,
    ModTime:  time.Now(),
    AccessTime: time.Now(),
    ChangeTime: time.Now(),
    Format:   tar.FormatPAX,
}
err := tw.WriteHeader(hdr)