Get assigned post categories

Question

I've created have a custom post type called "Crew", like so:

function crew_custom_post_type() {

  $labels = array(
    'name'                  => _x( 'Pages', 'Post Type General Name', 'project' ),
    'singular_name'         => _x( 'Page', 'Post Type Singular Name', 'project' ),
    'menu_name'             => __( 'Crew', 'project' ),
    'name_admin_bar'        => __( 'Crew', 'project' ),
    'archives'              => __( 'Item Archives', 'project' ),
    'attributes'            => __( 'Item Attributes', 'project' ),
    'parent_item_colon'     => __( 'Parent Item:', 'project' ),
    'all_items'             => __( 'All Items', 'project' ),
    'add_new_item'          => __( 'Add New Item', 'project' ),
    'add_new'               => __( 'Add New', 'project' ),
    'new_item'              => __( 'New Item', 'project' ),
    'edit_item'             => __( 'Edit Item', 'project' ),
    'update_item'           => __( 'Update Item', 'project' ),
    'view_item'             => __( 'View Item', 'project' ),
    'view_items'            => __( 'View Items', 'project' ),
    'search_items'          => __( 'Search Item', 'project' ),
    'not_found'             => __( 'Not found', 'project' ),
    'not_found_in_trash'    => __( 'Not found in Trash', 'project' ),
    'featured_image'        => __( 'Featured Image', 'project' ),
    'set_featured_image'    => __( 'Set featured image', 'project' ),
    'remove_featured_image' => __( 'Remove featured image', 'project' ),
    'use_featured_image'    => __( 'Use as featured image', 'project' ),
    'insert_into_item'      => __( 'Insert into item', 'project' ),
    'uploaded_to_this_item' => __( 'Uploaded to this item', 'project' ),
    'items_list'            => __( 'Items list', 'project' ),
    'items_list_navigation' => __( 'Items list navigation', 'project' ),
    'filter_items_list'     => __( 'Filter items list', 'project' ),
  );
  $args = array(
    'label'                 => __( 'Page', 'project' ),
    'description'           => __( 'Post Type for Crew', 'project' ),
    'labels'                => $labels,
    'supports'              => array( 'title','author' ),
    'taxonomies'            => array( 'crew' ),
    'hierarchical'          => true,
    'public'                => true,
    'show_ui'               => true,
    'show_in_menu'          => true,
    'menu_position'         => 5,
    'show_in_admin_bar'     => true,
    'show_in_nav_menus'     => true,
    'can_export'            => true,
    'has_archive'           => true,
    'exclude_from_search'   => false,
    'publicly_queryable'    => true,
    'capability_type'       => 'page',
  );
  register_post_type( 'crew', $args );

}
add_action( 'init', 'crew_custom_post_type', 0 );

I've then created a taxonomy:

function crew_taxonomy() {

  $labels = array(
    'name'                       => _x( 'Categories', 'Taxonomy General Name', 'project' ),
    'singular_name'              => _x( 'Category', 'Taxonomy Singular Name', 'sabsound' ),
    'menu_name'                  => __( 'Categories', 'sabsound' ),
    'all_items'                  => __( 'All Items', 'sabsound' ),
    'parent_item'                => __( 'Parent Item', 'sabsound' ),
    'parent_item_colon'          => __( 'Parent Item:', 'sabsound' ),
    'new_item_name'              => __( 'New Item Name', 'sabsound' ),
    'add_new_item'               => __( 'Add New Item', 'sabsound' ),
    'edit_item'                  => __( 'Edit Item', 'sabsound' ),
    'update_item'                => __( 'Update Item', 'sabsound' ),
    'view_item'                  => __( 'View Item', 'sabsound' ),
    'separate_items_with_commas' => __( 'Separate items with commas', 'sabsound' ),
    'add_or_remove_items'        => __( 'Add or remove items', 'sabsound' ),
    'choose_from_most_used'      => __( 'Choose from the most used', 'sabsound' ),
    'popular_items'              => __( 'Popular Items', 'sabsound' ),
    'search_items'               => __( 'Search Items', 'sabsound' ),
    'not_found'                  => __( 'Not Found', 'sabsound' ),
    'no_terms'                   => __( 'No items', 'sabsound' ),
    'items_list'                 => __( 'Items list', 'sabsound' ),
    'items_list_navigation'      => __( 'Items list navigation', 'sabsound' ),
  );
  $args = array(
    'labels'                     => $labels,
    'hierarchical'               => true,
    'public'                     => true,
    'show_ui'                    => true,
    'show_admin_column'          => true,
    'show_in_nav_menus'          => true,
    'show_tagcloud'              => true,
  );
  register_taxonomy( 'crew', array( 'crew' ), $args );

}
add_action( 'init', 'crew_taxonomy', 0 );

I've created a whole bunch of categories and assigned them to posts within the crew custom post type.

On the archive page, I would like to output the assigned categories for each post.

I've tried the following on archive-crew.php:

<?php

  // Begin loop
  while ( have_posts() ): the_post();

  // Get assigned categories for each post
  $post_id = get_the_ID();
  $array = array(
    'taxonomy' => 'crew',
  );

  $categories = wp_get_post_categories( $post_id, $array );

?>


  <?php
    echo '<h2>'.get_the_title().'</h2>';
    echo '<p>'.$categories.'</p>';
  ?>


<?php // End loop
  endwhile;
?>

The above doesn't return anything. I'm simply looking to list the child categories for filtering without any html around it.

Answer 1

wp_get_post_categories() is only for Core Categories - not custom taxonomies. Try wp_get_post_terms(). :)