nestjs-i18n

What is nestjs-i18n?

nestjs-i18n is a powerful internationalization (i18n) module for NestJS applications. It provides a comprehensive set of tools to manage translations, handle localization, and support multiple languages in a NestJS application.

What are nestjs-i18n's main functionalities?

Basic Setup

This code sets up the basic configuration for nestjs-i18n. It initializes the I18nModule with a fallback language and specifies the parser and the path to the translation files.

```typescript
import { Module } from '@nestjs/common';
import { I18nModule, I18nJsonParser } from 'nestjs-i18n';
import * as path from 'path';

@Module({
  imports: [
    I18nModule.forRoot({
      fallbackLanguage: 'en',
      parser: I18nJsonParser,
      parserOptions: {
        path: path.join(__dirname, '/i18n/'),
      },
    }),
  ],
})
export class AppModule {}
```

Translation Service

This code demonstrates how to use the I18nService to translate a message. The `translate` method is used to fetch the translation for the given key ('HELLO_MESSAGE').

```typescript
import { Injectable } from '@nestjs/common';
import { I18nService } from 'nestjs-i18n';

@Injectable()
export class AppService {
  constructor(private readonly i18n: I18nService) {}

  async getHello(): Promise<string> {
    return this.i18n.translate('HELLO_MESSAGE');
  }
}
```

Request Scoped Translations

This code shows how to use request-scoped translations. By injecting the I18nContext into the controller method, you can translate messages based on the current request's language.

```typescript
import { Controller, Get } from '@nestjs/common';
import { I18n, I18nContext } from 'nestjs-i18n';

@Controller()
export class AppController {
  @Get()
  async getHello(@I18n() i18n: I18nContext): Promise<string> {
    return i18n.translate('HELLO_MESSAGE');
  }
}
```

Other packages similar to nestjs-i18n

i18next

i18next is a popular internationalization framework for JavaScript applications. It provides a wide range of features for managing translations and supports various backends for loading translation files. Compared to nestjs-i18n, i18next is more general-purpose and can be used with any JavaScript framework, not just NestJS.

nestjs-i18n

nestjs-i18n is another internationalization module for NestJS. It offers similar functionalities to nestjs-i18n, such as managing translations and supporting multiple languages. However, it may have different configuration options and features.

react-i18next

react-i18next is a powerful internationalization library specifically designed for React applications. It builds on top of i18next and provides React-specific bindings. While it offers similar translation management features, it is tailored for use with React rather than NestJS.

README

Description

The i18n module for Nest.

Installation

$ npm i --save nestjs-i18n

Quick Start

Structure

create a directory and in it define your language keys as directories. When using BY_LANGUAGE you can also define global translations. This is useful for things that are the same in each language for example your company name. Each file that is in the root of your i18n folder will be defined globally. You can overwrite global translations by defining them within a language.

i18n
├── en
│   ├── category.json
│   └── auth.json
├── nl
│   ├── category.json
│   └── auth.json
└── global.json

Translation file

The format for the translation file could look like this:

{
  "HELLO_MESSAGE": "Hello {username}",
  "GOODBYE_MESSAGE": "Goodbye {username}",
  "USER_ADDED_PRODUCT": "{0.username} added {1.productName} to cart",
  "SETUP": {
    "WELCOME": "Welcome {0.username}",
    "GOODBYE": "Goodbye {0.username}"
  },
  "ARRAY": [
    "ONE",
    "TWO",
    "THREE"
  ]
}

String formatting is done by: string-format

Translation module

To use the translation service we first add the module. The I18nModule has an @Global() attribute so you should only import it once.

import { Module } from '@nestjs/common';
import * as path from 'path';
import { I18nModule } from 'nestjs-i18n';

@Module({
  imports: [
    I18nModule.forRoot({
      path: path.join(__dirname, '/i18n'), 
      filePattern: '*.json',
      fallbackLanguage: 'en',
    }),
  ],
  controllers: []
})
export class AppModule {}

using forRootAsync

import { Module } from '@nestjs/common';
import * as path from 'path';
import { I18nModule } from 'nestjs-i18n';

@Module({
  imports: [
    I18nModule.forRootAsync({ 
        useFactory: (config: ConfigurationService) => ({ 
          path: configService.i18nPath, 
          fallbackLanguage: configService.fallbackLanguage, // e.g., 'en'
          filePattern: configService.i18nFilePattern, // e.g., '*.i18n.json'
        }),
        inject: [ConfigurationService] 
    }),
  ],
  controllers: []
})
export class AppModule {}

Using translation service

@Controller()
export class SampleController {

  constructor(
    private readonly i18n: I18nService,
  ) {}

  @Get()
  sample() {
    this.i18n.translate('en', 'HELLO_MESSAGE', {id: 1, username: 'Toon'});
    this.i18n.translate('en', 'SETUP.WELCOME', {id: 1, username: 'Toon'});
    this.i18n.translate('en', 'ARRAY.0');
  }
}

Breaking changes:

• from V3.0.0 on we load translations based on their directory name instead of file name. Change your translations files to the structure above: info