switch_to_blog() breaks custom post type permalinks

[sickhippie]

When using switch_to_blog() and custom post types, there are very strange results when calling the_permalink() or get_permalink(). For reference, we'll say the root site is blog1 and the second site containing the posts is blog2.

Using this code inside the loop:

switch_to_blog( $post->blog_id );
get_permalink();

If the post type is not registered on the current blog, the permalink given will be sitename.com/blog2/slug - when clicking it as href, it brings you the first instance of that slug in the database.

If the post type is registered on the current blog, the permalink given will be sitename.com/blog2/blog1/post-type/slug - this link will 404.

Related issue: #14992

[SergeyBiryukov]

Related: #12040

[wonderboymusic]

"sitename.com/blog2/blog1/post-type/slug" - in trunk this doesn't happen, I get this: ​http://wordpress-core/second/stuff/test-me/

[jaroat]

Sorry - I can clearly reproduce that behaviour in a current (directory-based) multisite-project:

As-Is State:

• WP 3.4.2
• Directory based Multisite installation
• Custom Post Type "clipping" was registered in all blogs
• Actual clipping-entries lie in blog_id 2
• main blog address is "mydomain.tld/blog"
• blog 2 address is "mydomain.tld/verband"

home-template of main-blog:

switch_to_blog(2);
$clipping_id = get_id_from_some_function();
$clipping_url = get_permalink($clipping_id);
restore_current_blog();

Problem:

$clipping_url / permalink returned is:

​http:// mydomain.tld /verband /blog /slug-of-post-type /slug-of-clipping

I narrowed this down to the function get_extra_permastruct (wp-includes/rewrite.php) called in function get_post_permalink (wp-includes/link-template.php), which wrongly prepends "/blog" to all clipping slugs.

get_permalink does of course correctly work in templates of blog 2.

Wild assumption

Seems that get_extra_permastruct does not know that it has to act in the context of blog 2 after using switch_to_blog.

br from Salzburg,

• Johannes

[jaroat]

Seems that get_permalink for custom post types depends on get_extra_permastruct in wp-includes/rewrite.php and acts wrongly if the target custom post types was registered with the "with_front" parameter (or without: with_front=1 is default).

get_extra_permastruct relies on it's internal var extra_permastructs which doesn't get updated to the new context when calling switch_to_blog.

So all permalinks fetched after switch_to_blog get constructed in the rewrite-context of the original blog calling the function - not the blog context the programmer switched to.

br from Salzburg,

• Johannes

[jeremyfelt]

I can reproduce on current trunk.

Also of note: If the post type is only registered on blog ID 2, and you ask for the permalink from blog ID 1, the default post structure is returned because blog ID 1 is not aware that clippings exists.

I can't imagine a fix for this being possible without every site in a network installation being able to generate the rewrite rules of every other site on demand. With all of the methods available around creating and modifying rewrite rules, this does not seem plausible.

I can start to imagine some creative ways of solving this on individual setups. I think that's more appropriate here.

Suggesting wontfix.

[jeremyfelt]

Closing as wontfix. No feedback after 8 months and this doesn't seem plausible.

[danielpataki]

We "fixed" this issue by looking at rewrite rules. This works for our purposes but I haven't done extensive research to see if this would break anywhere. Perhaps it can spark some interest though.

<?php
    switch_to_blog(3);
    $url = get_permalink(1234);
    $post_type = get_post_type(1234);
    $post_type_object = get_post_type_object($post_type);

    if(!empty($post_type_object->rewrite) && array_key_exists('slug', $post_type_object->rewrite) ) {
      $rewrite = get_option('rewrite_rules');
      $rule = array_search('index.php?post_type=' . $post_type, $rewrite);
      $base = str_replace('/?$', '', $rule);
      $url = str_replace('/' . $post_type_object->rewrite['slug'] . '/', '/' . $base . '/', $url);
    }

    $translations[$i]['url'] = $url;
    restore_current_blog();

This is not quite the exact code we use but it's a useful example. I'm super unsure about the quick and dirty str_replace bits at the end, it feels like spit and duct tape. I hope this is useful for someone, if anyone has a better idea, it would be great to get this one moving :)

[SergeyBiryukov]

#38305 was marked as a duplicate.

[SergeyBiryukov]

Might be related: #29039, #12002.

[SergeyBiryukov]

#49309 was marked as a duplicate.

[mennoll]

I was able to make a fix you can put in your themes functions.php file.
It works when your permalink structure is set to /%postname%/ .
I have not tested other permalink structures, but maybe this can still help you to find the right solution.

<?php
        /**
         * Fix multisite custom post type permalinks after switching blogs
         * @see https://core.trac.wordpress.org/ticket/20861
         *
         * @param string $post_link
         * @param WP_Post $post
         * @return string
         */
         function fix_multisite_cpt_permalinks( $post_link, $post ) {
                // Only run if switched to other site
                if ( ! isset( $GLOBALS['switched'] ) || ! $GLOBALS['switched'] || empty( $GLOBALS['_wp_switched_stack'] ) ) {
                        return $post_link;
                }

                // Only run if permalink structure is %postname%
                $current_permalink_structure = get_option( 'permalink_structure' );
                if ( $current_permalink_structure !== '/%postname%/' ) {
                        return $post_link;
                }

                // Get post type url prefix
                $url_prefix       = $post->post_type;
                $post_type_object = get_post_type_object( $post->post_type );
                if ( $post_type_object instanceof WP_Post_Type && ! empty( $post_type_object->rewrite ) && array_key_exists( 'slug', $post_type_object->rewrite ) ) {
                        $url_prefix = $post_type_object->rewrite['slug'];
                }

                // Generate post permalink
                $post_link = home_url( '/' . $url_prefix . '/' . $post->post_name . '/' );

                return $post_link;
        }
        add_filter( 'post_type_link', 'fix_multisite_cpt_permalinks', 10, 2 );