Documentation: t Function in adonis-intlayer

The t function in the adonis-intlayer package is the core utility for providing localised responses in your AdonisJS application. It simplifies internationalisation (i18n) by dynamically selecting content based on the user's preferred language.

Overview

The t function is used to define and retrieve translations for a given set of languages. It automatically determines the appropriate language to return based on the client's request settings, such as the Accept-Language header. If the preferred language is unavailable, it gracefully falls back to the default locale specified in your configuration.

Key Features

• Dynamic Localisation: Automatically selects the most appropriate translation for the client.
• Fallback to Default Locale: Falls back to a default locale if the client's preferred language isn't available, ensuring continuity in user experience.
• Asynchronous Context: Works seamlessly within the AdonisJS request lifecycle using Async Local Storage.
• TypeScript Support: Enforce type safety for your translations.

Function Signature

t(translations: Record<string, any>): any;

Parameters

• translations: An object where the keys are locale codes (e.g., en, fr, es) and the values are the corresponding translated content.

Returns

• The content representing the client's preferred language.

Loading the Middleware

To ensure that the t function works correctly, you must register the intlayer middleware in your AdonisJS application.

router.use([() => import("adonis-intlayer/middleware")]);

Usage Examples

Basic Example

import router from "@adonisjs/core/services/router";
import { t } from "adonis-intlayer";

router.get("/", async () => {
  return t({
    en: "Welcome!",
    fr: "Bienvenue!",
    es: "¡Bienvenido!",
  });
});

Usage in Controllers

import type { HttpContext } from "@adonisjs/core/http";
import { t } from "adonis-intlayer";

export default class ExampleController {
  async index({ response }: HttpContext) {
    return response.send(
      t({
        en: "Hello from controller",
        fr: "Bonjour depuis le contrôleur",
      })
    );
  }
}

Advanced Topics

Fallback Mechanism

If a preferred locale is unavailable, the t function will fallback to the default locale defined in your intlayer.config.ts.

import { Locales, type IntlayerConfig } from "intlayer";

const config: IntlayerConfig = {
  internationalization: {
    locales: [
      Locales.ENGLISH,
      Locales.RUSSIAN,
      Locales.JAPANESE,
      Locales.FRENCH,
      Locales.KOREAN,
      Locales.CHINESE,
      Locales.SPANISH,
      Locales.GERMAN,
      Locales.ARABIC,
      Locales.ITALIAN,
      Locales.ENGLISH_UNITED_KINGDOM,
      Locales.PORTUGUESE,
      Locales.HINDI,
      Locales.TURKISH,
      Locales.POLISH,
      Locales.INDONESIAN,
      Locales.VIETNAMESE,
      Locales.UKRAINIAN,
    ],
    defaultLocale: Locales.ENGLISH,
  },
};

export default config;

TypeScript Integration

The t function is type-safe when used with defined dictionaries. For more details, refer to the TypeScript documentation.