Internationalization

The Tempura library provides the functionality for internationalization and translation.

We'd need to add it to the project.clj dependencies:

[com.taoensso/tempura "1.0.0"]

We can now require Tempura in the namespace we wish to use for internationalization:

(ns <app>.i18n
 (:require [taoensso.tempura :as tempura :refer [tr]]))

We'll create a dictionary map such as the one below.

(def tconfig
  {:dict
   {:en-US
    {:missing ":en-GB missing text"
     :page {:title "Here is a title"
            :content "Time to start building your site."}}
    :fr-FR
    {:page {:title "Voici un titre"
            :content "Il est temps de commencer votre site."}}}})

We can use the translation function directly as follows:

(tr tconfig [:en-US :fr-FR] [:page/title])
 

We can also add the Tempura middleware wrapper to our handler with the above config in our middleware namespace. We'll have to require taoensso.tempura and add the new middleware wrapper to wrap-base as follows: the wrap-base function.

(ns <app>.middleware
  (:require [taoensso.tempura :as tempura :refer [tr]]
            ...))

(defn wrap-i18n [handler]
  (tempura/wrap-ring-request handler {:tr-opts tconfig}))

(defn wrap-base [handler]
  (-> handler
      wrap-i18n
      ...))

The middleware uses the Accept-Language HTTP header to infer the preferred locale for the client. The middleware will append two keys to the request. The first key is :tempura/accept-langs that contains a vector of keys parsed from the request, e.g: ["en-ES" "en-US"]. The second key is :tempura/tr and it contains the translations function initialized with the tconfig and the locales from the request. The locale middleware will use the first available locale contained in the :tempura/accept-langs key.

With the middleware setup, we can now use translations in our pages as seen below.

(ns mysite.routes.home
  (:require [i18ntest.layout :as layout]
            [i18ntest.util :as util]))

(defn home-page [request {tr :tempura/tr}]
  (layout/render
    request
    "home.html" {:title   (tr [:page/title])
                 :content (tr [:page/content])}))

(defn about-page [request]
  (layout/render request "about.html"))

(def home-routes
  [["/" {:get home-page request}]
   ["/about" {:get about-page}]])

See the official Github project page for more details on Tempura usage.

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