Getting the locale from browser data

In order to improve the user experience on a website, it's important to display information in a format that is acceptable in the user's locale. Locale is a generic term used to indicate an area of the world. An effort in the I.T. community has been made to codify locales using a two-part designation consisting of codes for both language and country. But when a person visits your website, how do you know their locale? Probably the most useful technique involves examining the HTTP language header.

How to do it...

In order to encapsulate locale functionality, we will assume a class, Application\I18n\Locale. We will have this class extend an existing class, Locale, which is part of the PHP Intl extension.
Note
I18n is a common abbreviation for Internationalization. (Count the number of letters!)
```
namespace Application\I18n;
use Locale as PhpLocale;
class Locale extends PhpLocale
{
  const FALLBACK_LOCALE = 'en';
  // some code
}
```
To get an idea of what an incoming request looks like, use phpinfo(INFO_VARIABLES). Be sure to disable this function immediately after testing as it gives away too much information to potential attackers:
```
<?php phpinfo(INFO_VARIABLES); ?>
```

Locale information is stored in $_SERVER['HTTP_ACCEPT_LANGUAGE']. The value will take this general form: ll-CC,rl;q=0.n, ll-CC,rl;q=0.n, as defined in this table:

Abbreviation	Meaning
`ll`	Two-character lowercase code representing the language.
`-`	Separates language from country in the locale code `ll-CC`.
`CC`	Two-character uppercase code representing the country.
`,`	Separates locale code from fallback root locale code (usually the same as the language code).
`rl`	Two-character lowercase code representing the suggested root locale.
`;`	Separates locale information from quality. If quality is missing, default is `q=1` (100%) probability; this is preferred.
`q`	Quality.
`0.n`	Some value between 0.00 and 1.0. Multiply this value by 100 to get the percentage of probability that this is the actual language preferred by this visitor.

There can easily be more than one locale listed. For example, the website visitor could have multiple languages installed on their computer. It so happens that the PHP Locale class has a method, acceptFromHttp(), which reads the Accept-language header string and gives us the desired setting:
```
protected $localeCode;
public function setLocaleCode($acceptLangHeader)
{
  $this->localeCode = $this->acceptFromHttp($acceptLangHeader);
}
```

We can then define the appropriate getters. The get AcceptLanguage() method returns the value from $_SERVER['HTTP_ACCEPT_LANGUAGE']:

public function getAcceptLanguage()
{
  return $_SERVER['HTTP_ACCEPT_LANGUAGE'] ?? self::FALLBACK_LOCALE;
}
public function getLocaleCode()
{
  return $this->localeCode;
}

Next we define a constructor that allows us to "manually" set the locale. Otherwise, the locale information is drawn from the browser:

public function __construct($localeString = NULL)
{
  if ($localeString) {
    $this->setLocaleCode($localeString);
  } else {
    $this->setLocaleCode($this->getAcceptLanguage());
  }
}

Now comes the big decision: what to do with this information! This is covered in the next few recipes.

Note

Even though a visitor appears to accept one or more languages, that visitor does not necessarily want contents in the language/locale indicated by their browser. Accordingly, although you can certainly set the locale given this information, you should also provide them with a static list of alternative languages.

How it works...

In this illustration, let's take three examples:

information derived from the browser
a preset locale fr-FR
a string taken from RFC 2616: da, en-gb;q=0.8, en;q=0.7

Place the code from steps 1 to 6 into a file, Locale.php, which is in the Application\I18n folder.

Next, create a file, chap_08_getting_locale_from_browser.php, which sets up autoloading and uses the new class:

<?php
  require __DIR__ . '/../Application/Autoload/Loader.php';
  Application\Autoload\Loader::init(__DIR__ . '/..');
  use Application\I18n\Locale;

Now you can define an array with the three test locale strings:

$locale = [NULL, 'fr-FR', 'da, en-gb;q=0.8, en;q=0.7'];

Finally, loop through the three locale strings, creating instances of the new class. Echo the value returned from getLocaleCode() to see what choice was made:

echo '<table>';
foreach ($locale as $code) {
  $locale = new Locale($code); 
  echo '<tr>
    <td>' . htmlspecialchars($code) . '</td>
    <td>' . $locale->getLocaleCode() . '</td>
  </tr>';
}
echo '</table>';

Here is the result (with a little bit of styling):

Table of Contents for
PHP 7: Real World Application Development

Getting the locale from browser data

How to do it...

Note

Note

How it works...

See also

Table of Contents for PHP 7: Real World Application Development

Getting the locale from browser data

How to do it...

Note

Note

How it works...

See also

Table of Contents for
PHP 7: Real World Application Development