Go Language

Date and Time Formatting in Golang

Learn how to format a date in Go, using format constants or a custom format

Golang Community Moderator. Software Engineer - Open Source Enthusiast. Goper Lover

Published · Oct 20 2019

  

In Go, the current time can be determined using time.Now(), provided by the time package.
t := time.Now()

This will print the system local time. Want UTC instead? append .UTC():

The time can be formatted using the time.Format() method:
t := time.Now().UTC()

Want the timestamp?
t := time.Now().Unix()

. . .
Use a custom format
An example of formatting with a custom format is:
package main

import (
	"fmt"
	"time"
)

func main() {
	t := time.Now().UTC()
	fmt.Println(t.Format("2006-01-02 15:04:05"))

}

https://play.golang.org/p/BRLdfBGW3UI

That 2006-01-02 15:04:05 string looks strange, isn’t it? It’s not like it’s 2006 now! 
But it will print 
2009-11-10 23:00:00

If you’re new to Go, this will sound very strange. Here’s the explanation: Go’s time formatting is unique and different than what you would do in other languages. 

Instead of having a conventional format to print the date, Go uses the reference date 20060102150405 which seems meaningless but actually has a reason, as it’s 1 2 3 4 5 6 in the Posix date command:
Mon Jan 2 15:04:05 -0700 MST 2006
0   1   2  3  4  5              6

The timezone in the middle would have been the 7 (not really sure why they didn’t pick Mon Jan 2 03:04:05 -0600 MST 2007, by the way)
Interesting historical reference: https://github.com/golang/go/issues/444
. . .
Use a format constants
Go provides in the time package some handy constants for commonly used formats:
const (
        ANSIC       = "Mon Jan _2 15:04:05 2006"
        UnixDate    = "Mon Jan _2 15:04:05 MST 2006"
        RubyDate    = "Mon Jan 02 15:04:05 -0700 2006"
        RFC822      = "02 Jan 06 15:04 MST"
        RFC822Z     = "02 Jan 06 15:04 -0700" // RFC822 with numeric zone
        RFC850      = "Monday, 02-Jan-06 15:04:05 MST"
        RFC1123     = "Mon, 02 Jan 2006 15:04:05 MST"
        RFC1123Z    = "Mon, 02 Jan 2006 15:04:05 -0700" // RFC1123 with numeric zone
        RFC3339     = "2006-01-02T15:04:05Z07:00"
        RFC3339Nano = "2006-01-02T15:04:05.999999999Z07:00"
        Kitchen     = "3:04PM"
        // Handy time stamps.
        Stamp      = "Jan _2 15:04:05"
        StampMilli = "Jan _2 15:04:05.000"
        StampMicro = "Jan _2 15:04:05.000000"
        StampNano  = "Jan _2 15:04:05.000000000"
)

You can use them like this:
package main

import (
	"fmt"
	"time"
)

func main() {
	t := time.Now()
	fmt.Println("ANSIC: ", t.Format(time.ANSIC))

	fmt.Println("RubyDate: ", t.Format(time.RubyDate))
	fmt.Println("UnixDate: ", t.Format(time.UnixDate))

}

https://play.golang.org/p/34C5cME2WZe