Wordpress custom post type permalinks not working in Advanced Custom Fields post object field

Question

I am having the following issues with rendering custom permalinks using WordPress, the Advanced Custom Fields post object field and Timber. I have posts and a custom post type photo galleries that are related and are connected by a link setup using the post object field attached to the story post. The rendered links are being displayed like this: http://example.com/photos/%locations%/bordeaux/. The %locations% segment should be replaced by world/france in this example.

The permalinks are properly rendered when access using the post's permalink (http://example.com/photos/world/france/bordeaux), attached to a WordPress menu or navigated to using the core search functionality.

The post object has the following parameters set:

Filter by Post Type: Photo Gallery (custom post type)
Return Format: Post Object

I have included my custom post type, taxonomy, and post_type_link functions below.

Custom post type (abbreviated)

function gerryfeehan_register_photos_post_type() {
  $args = [
    'label' => 'Photo Galleries',
    'labels' => [],
    'supports' => array(),
    'public' => true,
    'menu_position' => 5,
    'menu_icon' => 'dashicons-format-gallery',
    'capability_type' => 'post',
    'taxonomies' => [ 'locations', ],
    'has_archive' => true,
    'delete_with_user' => false,
    'rewrite' => [
        'slug' => 'photos/%locations%',
        'with_front' => false,
    ],
  ];
  register_post_type( 'photos', $args );
}
add_action( 'init', 'gerryfeehan_register_photos_post_type' );

Custom taxonomy (abbreviated)

function gerryfeehan_register_locations_taxonomy() {
  $args = [
    'labels' => [],
    'hierarchical' => true,
    'rewrite' => [
        'slug' => 'locations',
        'hierarchical' => true,
    ],
  ];
  register_taxonomy( 'locations', [ 'photos' ], $args );
}
add_action( 'init', 'gerryfeehan_register_locations_taxonomy' );

Post type link filter function

add_filter( 'post_type_link', 'gerryfeehan_post_type_link', 10, 2 );
function gerryfeehan_post_type_link( $post_link ) {
  $taxonomy = 'locations';
  $terms = get_the_terms( get_the_ID(), $taxonomy );
  $slug = [];
  // Warning: Invalid argument supplied for foreach()
  foreach ( $terms as $term ) {
    if ( $term->parent == 0 ) {
      array_unshift( $slug, sanitize_title_with_dashes( $term->name ) );
    } else {
      array_push( $slug, sanitize_title_with_dashes( $term->name ) );
    }
  }
  if ( ! empty( $slug ) ) {
    return str_replace( '%' . $taxonomy . '%' , join( '/', $slug ) , $post_link );
  }
  return $post_link;  
}

Timber get_field function

{{ story.get_field( 'associated_photo_gallery' ).link }}

Any suggestions on why the permalinks are not rendering correctly when being used by Advanced Custom Fields and Timber.

If you say "Any suggestions on why the permalinks are not rendering correctly", what is actually rendering? Do you get a wrong link or nothgin? What does {{ dump(story.get_field('associated_photo_gallery')) }} output? Is it an array that contains a link key? — Gchtr
@Gchtr The following was displayed in the template using dump example.com/photos/%location%/bordeaux. There was a PHP warning related to the post_type_link function. I have updated my question to include those details. I am not sure if the two are related. — Mike Hermary

Gchtr Gchtr · Accepted Answer · 2021-04-14T06:42:20

As far as I can see, your configuration for your custom permalink structure in register_post_type() looks fine.

The reason why you get an "Invalid argument supplied for foreach()" warning is because the post_type_link filter runs for every post type. But the locations taxonomy probably isn’t registered for every post type of your site and the get_the_terms() function returns false if there are no terms.

To fix this you should add a bailout that returns early when it’s not the photos post type. For that, you can use the $post parameter, that is provided as the second argument in the filter.

add_filter( 'post_type_link', 'gerryfeehan_post_type_link', 10, 2 );

function gerryfeehan_post_type_link( $post_link, $post ) {
    // Bail out if not photos post type.
    if ( 'photos' !== $post->post_type ) {
        return $post_link;
    }

    $taxonomy = 'locations';
    $terms    = get_the_terms( get_the_ID(), $taxonomy );
    $slug     = [];

    foreach ( $terms as $term ) {
        if ( $term->parent == 0 ) {
            array_unshift( $slug, sanitize_title_with_dashes( $term->name ) );
        } else {
            array_push( $slug, sanitize_title_with_dashes( $term->name ) );
        }
    }

    if ( ! empty( $slug ) ) {
        $post_link = str_replace( '%' . $taxonomy . '%', join( '/', $slug ), $post_link );
    }

    return $post_link;
}

Also, you need to make sure that you flush your permalinks by visiting the Settings → Permalinks page in the WordPress admin.

Wordpress custom post type permalinks not working in Advanced Custom Fields post object field

1 Answers