Introduction

A middleware to use i18next in koajs.

Getting started

install dependencies

npm install koa-i18next

working with backend

const koa = require('koa')
const i18next = require('i18next')
const Backend = require('i18next-sync-fs-backend') // or i18next-node-fs-backend
const koaI18next = require('koa-i18next')

i18next
  .use(Backend)
  .init({
    backend: {
      // translation resources
      loadPath: path.resolve('./locales/{{lng}}/{{ns}}.json'),
      addPath: path.resolve('./locales/{{lng}}/{{ns}}.missing.json')
    },
    preload: ['zh', 'en'], // must know what languages to use
    fallbackLng: 'en'
  })

const app = koa()
app.use(koaI18next(i18next, {
  lookupCookie: 'i18next', // detecting language in cookie
  /**
  * Detecting language in path params, need third part route middleware.
  * Example
  * path: `/api/:lng/hello
  */
  lookupPath: 'lng',
  lookupFromPathIndex: 0, // detecting language in path, like `/api/zh/hello` which `zh` is the language and the index is 1
  lookupQuerystring: 'lng', // detect language in query,
  lookupSession: 'lng', // detect language in session
  /**
  * support querystring, cookie, header, session, path
  * default order: ['querystring', 'cookie', 'header']
  */
  order: ['querystring'],
  next: true // if koa is version 2
}))
// [email protected]
app.use(function* (next) {
  this.body = {message: this.t('lalala')}
})

language detection

Support for:

• querystring
• cookie
• header
• session
• path

If you don't config this, it will use ['querystring', 'cookie', 'header'] as default detecting order.

options

{
  // order and from where user language should be detected
  order: ['querystring', 'cookie', 'header'/*, 'path', 'session'*/],
  // keys or params to lookup language from
  lookupQuerystring: 'lng',
  lookupCookie: 'i18next',
  lookupSession: 'lng',
  lookupPath: 'lng',
  lookupFromPathIndex: 0,
  // if koa is v2
  next: true
}

api

you can use i18next in koa middleware, as:

this.t('balabala', options)

i18next.t arguments are all supported. i18next.t

Resources middleware

inspired by i18next-express-middleware

If needed, you can serve the translations with the resources middleware.
As Koa doesn't come with built-in routing system, you'll have to handle the request path matching by a routing library or by specifying a path in the options.

const koaI18next = require('koa-i18next')
...
// Exemple without router
app.use(koaI18next.getResourcesHandler(i18next, {path: '/locales/resources.json'}));

// Exemple with koa-router
app.get('/locales/resources.json', koaI18next.getResourcesHandler(i18next));

Requesting /locales/resources.json?lng=en&ns=fr will return the translations of the common namespace of the en language.
Note: Multiple languages and namespaces are supported.

Available options (with default) are :

{
  // Serve resources only if ctx.path match given path (handle every request by default)
  path: false, 
  // Where to look for lng & ns parameters on the context (query, params, ...)
  propertyParam: 'query',   
  // Name of the lng param
  lngParam: 'lng',
  // Name of the ns param
  nsParam: 'ns'
}

Missing Keys middleware

inspired by i18next-express-middleware

You can handle missing keys with the Missing Keys middleware. It'll need the bodyparser in order to get the submitted missing translations.

const koaI18next = require('koa-i18next')
...
// Exemple without router
app.use(koaI18next.getMissingKeysHandler(i18next, {path: '/locales/add'}));

// Exemple with koa-router
app.post('/locales/add', koaI18next.getMissingKeysHandler(i18next));

Posting on /locales/add?lng=en&ns=common with an array of missing message as body will perform a save missing for the common namespace and the en language.

Available options (with default) are :

{
  // Handle request only if ctx.path match given path 
  path: false, 
  // Where to look for lng & ns parameters on the context (query, params, ...)
  propertyParam: 'query',   
  // Name of the lng params
  lngParam: 'lng',
  // Name of the ns param
  nsParam: 'ns'

}

License

MIT