i18n

The i18n package provides internationalization support using go-i18n/v2 . It loads YAML locale files, translates messages with template data, and detects the preferred language from HTTP request headers.

Import


import "github.com/gofastadev/gofasta/pkg/i18n"

Key Types

I18nService


type I18nService struct {
    bundle      *i18n.Bundle
    defaultLang string
}

Key Functions

Function	Signature	Description
`NewI18nService`	`func NewI18nService(localesDir string, defaultLang string) *I18nService`	Loads locale YAML files from the given directory
`T`	`func (s *I18nService) T(lang, messageID string, data map[string]interface{}) string`	Translates a message ID using the given language
`LangFromRequest`	`func (s I18nService) LangFromRequest(r http.Request) string`	Extracts the preferred language from the Accept-Language header
`CreateDefaultLocaleFile`	`func CreateDefaultLocaleFile(localesDir string)`	Creates a default English locale file if none exists

Translation Files

Create YAML translation files in your locales directory. Each file is named by its locale code.

locales/en.yaml:


welcome:
  other: "Welcome, {{.Name}}!"
not_found:
  other: "Resource not found"
unauthorized:
  other: "Authentication required"
forbidden:
  other: "You don't have permission to access this resource"
validation_failed:
  other: "Validation failed"
internal_error:
  other: "An internal error occurred"

locales/fr.yaml:


welcome:
  other: "Bienvenue, {{.Name}} !"
not_found:
  other: "Ressource introuvable"
unauthorized:
  other: "Authentification requise"

Usage

Basic Translation


translator := i18n.NewI18nService("locales/", "en")
 
msg := translator.T("en", "welcome", map[string]interface{}{"Name": "Jane"})
// -> "Welcome, Jane!"
 
msg = translator.T("fr", "welcome", map[string]interface{}{"Name": "Jane"})
// -> "Bienvenue, Jane !"

Fallback to Default Language

When a message is not found in the requested language, the service falls back to the default language:


// If "internal_error" is not in fr.yaml, falls back to en.yaml
msg := translator.T("fr", "internal_error", nil)
// -> "An internal error occurred"

Language Detection from Request


func (c *UserController) Create(w http.ResponseWriter, r *http.Request) {
    lang := c.translator.LangFromRequest(r)
 
    user, err := c.service.Create(r.Context(), input)
    if err != nil {
        msg := c.translator.T(lang, "internal_error", nil)
        httputil.Error(w, errors.BadRequest(msg))
        return
    }
 
    msg := c.translator.T(lang, "welcome", map[string]interface{}{"Name": user.Name})
    httputil.Created(w, msg, user)
}

Creating Default Locale Files

On first run, generate a default English locale file:


i18n.CreateDefaultLocaleFile("locales/")

Configuration via config.yaml


i18n:
  default_language: en
  locales_dir: locales/

Environment variables use the GOFASTA_ prefix (e.g., GOFASTA_I18N_DEFAULT_LANGUAGE).

Middleware — Locale detection middleware
Errors — Localized error messages
Mailer — Localized email templates