How to add a DropDown Language Picker (i18n) to the Menu

How-tos

2.0

i18n,AJAX,bootstrap,internationalization,bootstrap menu

# How To Add Internationalisation to the NavBar Menu in Yii2 Basic (Bootstrap 5)
 
Yii comes with internationalisation (**i18n**) "out of the box". There are instructions in the manual as to how to configure Yii to use i18n, but little information all in one place on how to fully integrate it into the bootstrap menu. This document attempts to remedy that. <img src="https://visualaccounts.co.uk/images/screenshots/Screenshot_i18n_s.png" />
 
 
The Github repository also contains the language flags, some country flags, a list of languages codes and their language names and a list of the languages Yii recognises "out of the box". A video will be posted on YouTube soon.
 
 
---
 
 
Ensure that your system is set up to use i18n. From the Yii2 Manual:
 
> Yii uses the `PHP intl` extension to provide most of its I18N features, such as the date and number formatting of the `yii\i18n\Formatter` class and the message formatting using `yii\i18n\MessageFormatter`. Both classes provide a fallback mechanism when the intl extension is not installed. However, the fallback implementation only works well for English target language. So it is highly recommended that you install `intl` when I18N is needed. ## Create the required Files
 
First you need to create a configuration file. Decide where to store it (e.g. in the `./messages/` directory with the name `create_i18n.php`). Create the directory in the project then issue the following command from **Terminal** (Windows: **CMD**) from the root directory of your project: ```php
 
./yii message/config-template ./messages/create_i18n.php
 
``` or for more granularity: ```php
 
./yii message/config --languages=en-US --sourcePath=@app --messagePath=messages ./messages/create_i18n.php
 
``` In the newly created file, alter (or create) the array of languages to be translated:
 
```php
// array, required, list of language codes that the extracted messages
// should be translated to. For example, ['zh-CN', 'de'].```

If necessary, change the root directory in `create_i18n.php` to point to the messages directory (- the default is `messages`).
 
Note, if the above file is in the messages directory (recommended) then don't alter this `'messagePath' => __DIR__,`.
 
If you alter the directory for `create_i18n.phpmessages` to, say, `/config/` (not a good idea) you can use the following:
 
```php // Root directory containing message translations. 'messagePath' => __DIR__ . DIRECTORY_SEPARATOR . 'config', ```
 
The created file should look something like this after editing the `languages` you need:
 
```php
<?php],
*/

 
/*
// 'db' output format is for saving messages to database.
'format' => 'db',// 'messageTable' => '{{%message}}',
*/

 
/*
// 'po' output format is for saving messages to gettext po files.
'format' => 'po',];
```

 
## Edit the `/config/web.php` file
 
In the `web.php` file, below `'id' => 'basic',` add:
 
```php 'language' => 'en', 'sourceLanguage' => 'en', ```
 
Note: you should always use the `'sourceLanguage' => 'en'` as it is, usually, easier and cheaper to translate from English into another language. If the `sourceLanguage` is not set it defaults to `'en'`.  Add the following to the `'components' => [...]` section:
 
```php
'i18n' => [
'translations' => [],
```

 
## Edit all the files in the "views" folder and any sub folders
 
Now tell Yii which text you want to translate in your view files. This is done by adding `Yii::t('app', 'text to be translated')` to the code. For example, in `/views/layouts/main.php`, change the menu labels like so:
 
```php
'items' => [
// ['label' => 'Home', 'url' => ['/site/index']], // Orignal code. Html::submitButton(
// 'Logout (' . Yii::$app->user->identity->username . ')', // change this line as well to the following:
Yii::t('app', 'Logout ({username})'), ['username' => Yii::$app->user->identity->username]),
['class' => 'nav-link btn btn-link logout']
)],
```

 
## Create the texts to be translated
 
To create the translation files, run the following, in **Terminal**, from the root directory of your project:
 
```php ./yii message ./messages/create_i18n.php ```
 
Now, get the messages translated. For example in the French `/messages/fr/app.php` >
 
```php >  'Home' => 'Accueil', >  'About' => 'À propos', >  ...
 
```
 
## Create a Menu Item (Dropdown) to Change the Language
 
This takes a number of steps.
 
### 1. Create an array of languages required
 
A `key` and a `name` is required for each language. The `key` is the ICU language code in lowercase (with optional [ISO 639.1](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes) in lowercase (with optional Country code [ISO 3166](https://en.wikipedia.org/wiki/List_of_ISO_3166_country _codes) in uppercase) e.g. 
 
>    French: `fr` or French Canada: `fr-CA` >
 
>    
 
>    Portuguese: `pt` or Portuguese Brazil: `pt-BR` The `name` is the name of the language *in that language*. Fe.g. for French: `'Français'`, for Japanese: `'日本の'`. *This is important* as the user may not understand the browser's current language. In `/config/params.php` create an array named `languages` with the languages required. For example:
 
```php
/* List of languages and their codes
*],
```

 
### 2. Create an Action
 
In `/controllers/SiteController.php`, the default controller, add an "Action" named `actionLanguage()`. This "Action" changes the language and sets a cookie so the browser "remembers" the language for page requests and return visits to the site.
 
```php
/**
* Called by the ajax handler to change the language and}
```

 
Remember to set the method to `POST`.
 
 In `behaviors()`, under `actions`, set `'language' => ['post'],` like so:
 
```php
'verbs' => [
'class' => VerbFilter::class,### 3. Create a Language Handler

 
Make sure that the correct language is served for each request. In the `/components/` directory`, create a file named: `LanguageHandler.php` and add the following code to it:
 
```php
<?php/* Location: ./components/LanguageHandler.php */
```

 
### 4. Call `LanguageHandler.php` from `/config/web.php`
 
"Call" the `LanguageHandler.php` file from `/config/web.php` by adding the following to either just above or just below `'params' => $params,`
 
```php
// Update the language on selection
'as beforeRequest' => [],
```

 
### 5. Add the Language Menu Item to `/views/layouts/main.php`
 
`main.php` uses Bootstrap to create the menu. An item (Dropdown) needs to be added to the menu to allow the user to select a language. Add `use yii\helpers\Url;` to the "uses" section of `main.php`. Just **above** `echo Nav::widget([...])` add the following code:
 
```php
// Get the languages and their keys, also the current route
foreach (Yii::$app->params['languages'] as $key => $language)}
```

 
In the section:
 
```php echo Nav::widget([...])` ```
 
between 
 
```php 'options' => ['class' => 'navbar-nav ms-auto'], // ms-auto aligns the menu right` ```
 
and 
 
```php 'items' => [...] ``` 
 
add: 
 
```php 'encodeLabels' => false, // Required to enter HTML into the labels ```
 
like so:
 
```php
echo Nav::widget([
'options' => ['class' => 'navbar-nav ms-auto'], // ms-auto aligns the menu right...
```

 
Now add the Dropdown. This can be placed anywhere in `'items' => [...]`.
 
```php
// Dropdown Nav Menu: https://www.yiiframework.com/doc/api/2.0/yii-widgets-menu
[],
```

 
The code for in `main.php` for the NavBar should look something like this:
 
```php
NavBar::begin([
'brandLabel' => Yii::$app->name, // set in /config/web.php```

If countryLanguage flags or images are required next to the language name see *Optional Items* at the end of this document. ### 6. Trigger the Language change with an Ajax call
 
To call the Language Action `actionLanguage()` make an Ajax call in a JavaScript file. Create a file in `/public_htmlweb/js/` named `language.js`. Add the following code to the file:
 
```jJavasScript
/*
* Copyright ©2023 JQL all rights reserved.});
```

 
To add the JavaScript file to the Assets, alter `/assets/AppAsset.php` in the project directory. In `public $js = []` add `'js/language.js',`, like so: >
 
```php >    public $js = [ >    'js/language.js', >    ]; >``` **Internationalisation should now be working on your project.**
 
 
 
--- ## Optional Items
 
The following are optional but may help both you and/or the user. ### 1. Check for Translations
 
Yii can check whether a translation is present for a particular piece of text in a `Yii::t('app', 'text to be translated')` block. There are two steps: 1.**A.** In `/config/web.php` * uncomment*` the following line:
 
```php // 'on missingTranslation' => ['app\components\TranslationEventHandler', 'handleMissingTranslation'], ``` 2.
 
**B.** Create a TranslationEventHandler: In `/components/` create a file named: `TranslationEventHandler.php` and add the following code to it:
 
```php
 
<?php

/**}
```

 
If there is a missing translation, the text is replaced with a message similar to the following text: > @MISSING: app.Logout (John) FOR LANGUAGE fr @ Here Yii has found that there is no French translation for:
 
```php Yii::t('app', 'Logout ({username})', ['username' => Yii::$app->user->identity->username]), ```
 
### 2. Add CountryLanguage Flags to the Dropdown Menu
 
This is very useful and recommended as it aids the User to locate the correct language. There are a number of steps for this. 1.
 
**a.** Create images of the flags. The images should be 25px wide by 15px high. The images **must have** the same name as the `language key` in the language array in `params.php`. For example: `fr.png` or `en-US.png`. If the images are not of type ".png" change the code in part 2**b.** below to the correct file extension. Place the images in a the directory `/public_htmlweb/images/flags/`. 2.**b.** Alter the code in `/views/layouts/main.php` so that the code for the "NavBar" reads as follows:
 
```php
<header id="header">
<?phpFor further reading and information see:

[i18ntutorial on Github](https://github.com/JQL/i18ntutorial)
 
 
[Yii2 Internationalization Tutorial](https://www.yiiframework.com/doc/guide/2.0/en/tutorial-i18n) [PHP intl extensions](https://www.php.net/manual/en/intro.intl.php) *---
 
 
If you use this code, please credit me as follows:*
 
> Internationalization (i18n) Menu code provided by JQL, https://visualaccounts.co.uk ©2023 JQL
 
--- ## Licence (BSD-3-Clause Licence)
 
Copyright Notice >
 
> Internationalization (i18n) Menu code provided by JQL, https://visualaccounts.co.uk ©2023 JQL all rights reserved

Redistribution and use in source and binary forms with or without modification are permitted provided that the following conditions are met:Neither the names of John Lavelle, JQL, Visual Accounts nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

"ALL JQL CODE & SOFTWARE INCLUDING WORLD WIDE WEB PAGES (AND THOSE OF IT'S AUTHORS) ARE SUPPLIED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND. TO THE MAXIMUM EXTENT PERMITTED BY LAW, THE AUTHOR AND PUBLISHER AND THEIR AGENTS SPECIFICALLY DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. WITH RESPECT TO THE CODE, THE AUTHOR AND PUBLISHER AND THEIR AGENTS SHALL HAVE NO LIABILITY WITH RESPECT TO ANY LOSS OR DAMAGE DIRECTLY OR INDIRECTLY ARISING OUT OF THE USE OF THE CODE EVEN IF THE AUTHOR AND/OR PUBLISHER AND THEIR AGENTS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. WITHOUT LIMITING THE FOREGOING, THE AUTHOR AND PUBLISHER AND THEIR AGENTS SHALL NOT BE LIABLE FOR ANY LOSS OF PROFIT, INTERRUPTION OF BUSINESS, DAMAGE TO EQUIPMENT OR DATA, INTERRUPTION OF OPERATIONS OR ANY OTHER COMMERCIAL DAMAGE, INCLUDING BUT NOT LIMITED TO DIRECT, INDIRECT, SPECIAL, INCIDENTAL, CONSEQUENTIAL OR OTHER DAMAGES."