Adding hreflang tags automatically in WordPress subdirectory multisite

 We have a WordPress MU subdirectory network setup:

• www.example.com - main website, USA, global
• www.example.com/uk/ - to display for UK visitors
• www.example.com/au/ - to display for Australian visitors.

We want to add hreflang tags for each webpage, and exclude the locations custom post type.

From this question, I've adjusted the code in the child theme's functions.php to:

function add_hreflang_attribute() {
   $site_url = network_site_url(); // base URL
   $alt_langs = array( '', 'au', 'uk' ); // two-letter language code
   $page_path = substr(get_permalink(), strlen(home_url('/'))); // path of page after base URL
   
   if (!( is_singular( 'locations' ) ) ) {
           
       // loop through the alternative languages, and get the appropriate hreflang tag for each that exists
       foreach ($alt_langs as $lang) {
           $updated_url_lang_path = $site_url . $lang . '/' . $page_path;
           $url_headers = @get_headers($updated_url_lang_path);
           if($url_headers && strpos( $url_headers[0], '200')) {
               if ($lang == 'uk') {
                   echo '<link rel="alternate" href="' . $updated_url_lang_path . '" hreflang="en-gb" />'. PHP_EOL;
               } elseif ($lang == '') {
                 
               }
               else {
                   echo '<link rel="alternate" href="' . $updated_url_lang_path . '" hreflang="en-' . $lang . '" />'. PHP_EOL;
               }
           }
       }
       
       // set primary as x-default
       echo '<link rel="alternate" href="' . $site_url . $page_path . '" hreflang="x-default" />';
        
   }

}

This code works on the main website's home page & example page: www.example.com/features/;

<link rel="alternate" href="https://www.example.com/au/features/" hreflang="en-au" />
<link rel="alternate" href="https://www.example.com/uk/features/" hreflang="en-gb" />
<link rel="alternate" href="https://www.example.com/features/" hreflang="x-default" />

and it works for the:

• AU site's home page,
• the AU site's features page: https://www.example.com/au/features/,

but on www.example.com/uk/ it only produces:

<link rel="alternate" href="https://www.example.com/au/" hreflang="en-au" />
<link rel="alternate" href="https://www.example.com/" hreflang="x-default" />

It is missing:

<link rel="alternate" href="https://www.example.com/uk/" hreflang="en-gb" />

The features page is a simple WordPress page.

Help appreciated.

EDIT

If I add if ($lang == 'uk') {print_r(get_headers($updated_url_lang_path));}, I see:

Array
(
    [0] => HTTP/1.1 200 OK
    [1] => Server: nginx
    [2] => Date: Wed, 11 May 2022 22:08:04 GMT
    [3] => Content-Type: text/html; charset=UTF-8
    [4] => Content-Length: 88422
    [5] => Connection: close
    [6] => Vary: Accept-Encoding
    [7] => Vary: Accept-Encoding
    [8] => Accept-CH: Sec-CH-UA-Mobile
    [9] => Link: <https://www.example.com/uk/wp-json/>; rel="https://api.w.org/"
    [10] => Link: <https://www.example.com/uk/wp-json/wp/v2/pages/10>; rel="alternate"; type="application/json"
    [11] => Link: <https://www.example.com/uk/>; rel=shortlink
    [12] => X-Powered-By: WP Engine
    [13] => X-Cacheable: SHORT
    [14] => Vary: Accept-Encoding,Cookie
    [15] => Cache-Control: max-age=600, must-revalidate
    [16] => X-Cache: HIT: 8
    [17] => X-Cache-Group: normal
    [18] => Accept-Ranges: bytes
    [19] => X-Orig-Cache-Control: no-cache
)

and the following is added properly:

<link rel="alternate" href="https://www.example.com/uk/" hreflang="en-gb" />

However, I only see this while logged into WordPress.

In an incognito window, at https://www.example.com/uk/ I see (only):

<link rel="alternate" href="https://www.example.com/" hreflang="x-default" />

phpwordpress

2 Answers

I

 altered the code to:

function mm_add_hreflang_attribute() {
    if (!( is_singular( 'locations' ) ) ) {
        $sites = array(
            array('', 'x-default'),
            array('en-gb/', 'en-gb'),
            array('en-au/', 'en-au'),
        );
        
        if ( is_post_type_archive('locations') ) {
            foreach ( $sites as $site ) {
                $site_url = network_site_url();
                $page_path = 'locations/';
                $geo_url = $site[0];
                $hreflang = $site[1];
                $url = $site_url . $geo_url . $page_path;
                echo '<link rel="alternate" href="' . $url . '" hreflang="' . $hreflang . '" />'. PHP_EOL;
            }
        } else {
            foreach ( $sites as $site ) {
                $site_url = network_site_url();
                $page_path = substr(get_permalink(), strlen(home_url('/')));
                $geo_url = $site[0];
                $hreflang = $site[1];
                $url = $site_url . $geo_url . $page_path;
                echo '<link rel="alternate" href="' . $url . '" hreflang="' . $hreflang . '" />'. PHP_EOL;
            }
        }
    }
}
add_action('wp_head', 'mm_add_hreflang_attribute', 1);

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How does this Facade works

 Question : 

The bounty expires in 6 hours. Answers to this question are eligible for a +50 reputation bounty. nagidi wants to draw more attention to this question.

I'm working with Laravel 5.8 and it's an Online Store project written by other programmers.

Basically I have faced something weird that never seen before.

Let's say we have this at a Controller method:

$payment = CourseRegistrationFacade::insertCourseRegisterInformation($courseId,$date,$memberId,$userId);

And then we goto the CourseRegistrationFacade and it goes like this:

class CourseRegistrationFacade extends BaseFacade
{
    
}

So the whole class is empty but it extends another Facade which is BaseFacade and it goes like this:

class BaseFacade extends Facade
{
    protected static function getFacadeAccessor()
    {
        return static::class;
    }

    protected static function shouldProxyTo($class)
    {
        app()->bind(self::getFacadeAccessor(), $class)
    }
}

And that's it !

I don't really know where the heal is insertCourseRegisterInformation !!

So if you know how this Facade works, please let me know...

---

Here is the full code of BaseFacade.php:

namespace App\Facades;

use Illuminate\Support\Facades\Facade;

class BaseFacade extends Facade
{
    protected static function getFacadeAccessor()
    {
        return static::class;
    }

    public static function shouldProxyTo($class)
    {
        app()->bind(self::getFacadeAccessor(), $class);
    }
}

Answers

Search in the code for:

CourseRegistrationFacade::shouldProxyTo(

Most likely in the service provider that line is somewhere registering that facade to some concrete implementation of a class. Then check the contents of the class (the argument passed to shouldProxyTo).

Inside that class there should be a method called insertCourseRegisterInformation.

The way facades work is they resolve the class out of the container and then call the method you call statically.

So for example, let's say you have a UserService.php with a method register() and that class is mapped to a UserServiceFacade.php. When you do UserServiceFacade::register(), __callStatic will get the facade accessor (actual class) from the container, then call the register() method of that class.

You can understand better by inspecting __callStatic inside Facade.php.

Essentially UserServiceFacade::register() is the same as doing:

$userService = app()->make(UserService::class);

$userService->register()

By using the facade you can hide the concrete implementation and could possibly switch it to something else in the future by just changing it in a single place.

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