Golang time zone list [duplicate] - go

Question

I'd like to write a method that will populate a Go Language array with the common timezones that are accepted by the time.Format() call, for use in an HTML template (Form select to allow them to read and choose their timezone). Is there a common way to do this?

Answer 1

To get a list of time zones, you can use something like:
package main
import (
"fmt"
"io/ioutil"
"strings"
)
var zoneDirs = []string{
// Update path according to your OS
"/usr/share/zoneinfo/",
"/usr/share/lib/zoneinfo/",
"/usr/lib/locale/TZ/",
}
var zoneDir string
func main() {
for _, zoneDir = range zoneDirs {
ReadFile("")
}
}
func ReadFile(path string) {
files, _ := ioutil.ReadDir(zoneDir + path)
for _, f := range files {
if f.Name() != strings.ToUpper(f.Name()[:1]) + f.Name()[1:] {
continue
}
if f.IsDir() {
ReadFile(path + "/" + f.Name())
} else {
fmt.Println((path + "/" + f.Name())[1:])
}
}
}
output:
Africa/Abidjan
Africa/Accra
Africa/Addis_Ababa
Africa/Algiers
Africa/Asmara
Africa/Asmera
Africa/Bamako
Africa/Bangui
...

Answer 2

Go's time pkg uses a timezone database.
You can load a timezone location like this:
loc, err := time.LoadLocation("America/Chicago")
if err != nil {
// handle error
}
t := time.Now().In(loc)
The Format function is not related to setting the time zone, this function takes a fixed reference time that allows you to format the date how you would like. Take a look at the time pkg docs.
For instance:
fmt.Println(t.Format("MST")) // outputs CST
Here is a running example

Answer 3

Here is an example: https://play.golang.org/p/KFGQiW5A1P-
package main
import (
"fmt"
"io/ioutil"
"strings"
"unicode"
)
func main() {
fmt.Println(GetOsTimeZones())
}
func GetOsTimeZones() []string {
var zones []string
var zoneDirs = []string{
// Update path according to your OS
"/usr/share/zoneinfo/",
"/usr/share/lib/zoneinfo/",
"/usr/lib/locale/TZ/",
}
for _, zd := range zoneDirs {
zones = walkTzDir(zd, zones)
for idx, zone := range zones {
zones[idx] = strings.ReplaceAll(zone, zd+"/", "")
}
}
return zones
}
func walkTzDir(path string, zones []string) []string {
fileInfos, err := ioutil.ReadDir(path)
if err != nil {
return zones
}
isAlpha := func(s string) bool {
for _, r := range s {
if !unicode.IsLetter(r) {
return false
}
}
return true
}
for _, info := range fileInfos {
if info.Name() != strings.ToUpper(info.Name()[:1])+info.Name()[1:] {
continue
}
if !isAlpha(info.Name()[:1]) {
continue
}
newPath := path + "/" + info.Name()
if info.IsDir() {
zones = walkTzDir(newPath, zones)
} else {
zones = append(zones, newPath)
}
}
return zones
}