How to embed and use .po files with gotext

[tslocum]

This functionality seems to be undocumented currently. The following code demonstrates how translations may be embedded, parsed and loaded.

LoadLocale should be called once at the very start of the application. A language may optionally be provided as forceLanguage, which skips device locale detection. Note that you will need replace any references to the boxcars domain with the domain used by your application. You may also need to modify the path to the .po files.

For a more complete example, see boxcars.

//go:embed locales
var assetFS embed.FS

func LoadLocale(forceLanguage *language.Tag) error {
	entries, err := assetFS.ReadDir("locales")
	if err != nil {
		return err
	}

	var available = []language.Tag{
		language.MustParse("en_US"),
	}
	for _, entry := range entries {
		if !entry.IsDir() {
			continue
		}
		available = append(available, language.MustParse(entry.Name()))
	}

	var preferred = []language.Tag{}
	if forceLanguage != nil {
		preferred = append(preferred, *forceLanguage)
	} else {
		systemLocale := os.Getenv("LANG")
		if systemLocale != "" {
			tag, err := language.Parse(systemLocale)
			if err == nil {
				preferred = append(preferred, tag)
			}
		}
	}

	useLanguage, _, _ := language.NewMatcher(available).Match(preferred...)
	useLanguageCode := useLanguage.String()
	if useLanguageCode == "" || strings.HasPrefix(useLanguageCode, "en") {
		return nil
	}

	b, err := assetFS.ReadFile(fmt.Sprintf("locales/%s/%s.po", strings.ReplaceAll(useLanguageCode, "-", "_"), strings.ReplaceAll(useLanguageCode, "-", "_")))
	if err != nil {
		return nil
	}

	po := gotext.NewPo()
	po.Parse(b)

	gotext.GetStorage().AddTranslator("boxcars", po)
	return nil
}