[wp-trac] [WordPress Trac] #58197: $blog_id always returns 0 in get_site_icon_url hook

[WordPress Trac]

#58197: $blog_id always returns 0 in get_site_icon_url hook
--------------------------+------------------------
 Reporter:  revxx14       |       Owner:  (none)
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  6.3
Component:  Customize     |     Version:  4.4
 Severity:  normal        |  Resolution:
 Keywords:  needs-patch   |     Focuses:  multisite
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Comment (by petitphp):

 @revxx14

 Yes it's confusing. Here `$blog_id` is not supposed to be equal to the
 current blog id, but to the blog id we are retrieving the site icon for.

 Here are some example with the different cases :
 {{{#!php
 <?php
 // Assuming the examples are run on the blog `7`

 // Case 1 : Retrieving the site icon url for the current site.
 // Here the value of `$blog_id` will be `0` and the value of
 `get_current_blog_id` will be `7`
 $icon_url = get_site_icon_url();

 // Case 2 : Retrieving the site icon url for the blog `12`.
 // Here the value of `$blog_id` will be `12`and the value of
 `get_current_blog_id` will be `7`
 $icon_url = get_site_icon_url( 512, '', 12 );

 // Case 3 : Retrieving the site icon url for the blog `7` (even if already
 on the blog `7`).
 // Here the value of `$blog_id` will be `7`and the value of
 `get_current_blog_id` will be `7`
 $icon_url = get_site_icon_url( 512, '', 7 );
 }}}

 The first case is the one used in WordPress core. That why you always have
 the value `0` for `$blog_id` when hooking the filter. If you see `0` it
 means we are getting the site icon url for the current site.

 Here one possible way this could be handled
 {{{#!php
 <?php
 function mytheme_set_site_icon_url(string $url, int $size, int $blog_id):
 string {
     // If `$blog_id` is `0`, fill it with the current blog id
     if ( empty( $blog_id ) ) {
         $blog_id = get_current_blog_id();
     }

     // Load the desired icon url
     switch ( $blog_id ) {
         case 7:
             $url =
 "https://example.com/7/my/custom/icon-{$size}x{$size}.svg"
             break;
         //...
     }

     return $url;
 }
 add_filter("get_site_icon_url", "mytheme_set_site_icon_url", 10, 3);
 }}}

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Ticket URL: <https://core.trac.wordpress.org/ticket/58197#comment:5>
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