get custom post type by taxonomy code example

Example 1: how to get texonomy catogory wise post

$custom_terms = get_terms('custom_taxonomy');

foreach($custom_terms as $custom_term) {
    wp_reset_query();
    $args = array('post_type' => 'custom_post_type',
        'tax_query' => array(
            array(
                'taxonomy' => 'custom_taxonomy',
                'field' => 'slug',
                'terms' => $custom_term->slug,
            ),
        ),
     );

     $loop = new WP_Query($args);
     if($loop->have_posts()) {
        echo '<h2>'.$custom_term->name.'</h2>';

        while($loop->have_posts()) : $loop->the_post();
            echo '<a href="'.get_permalink().'">'.get_the_title().'</a><br>';
        endwhile;
     }
}

Example 2: custom post type with taxonomy

//hook into the init action and call create_book_taxonomies when it fires
add_action( 'init', 'create_topics_hierarchical_taxonomy', 0 );
 
//create a custom taxonomy name it topics for your posts
 
function create_topics_hierarchical_taxonomy() {
 
// Add new taxonomy, make it hierarchical like categories
//first do the translations part for GUI
 
  $labels = array(
    'name' => _x( 'Topics', 'taxonomy general name' ),
    'singular_name' => _x( 'Topic', 'taxonomy singular name' ),
    'search_items' =>  __( 'Search Topics' ),
    'all_items' => __( 'All Topics' ),
    'parent_item' => __( 'Parent Topic' ),
    'parent_item_colon' => __( 'Parent Topic:' ),
    'edit_item' => __( 'Edit Topic' ), 
    'update_item' => __( 'Update Topic' ),
    'add_new_item' => __( 'Add New Topic' ),
    'new_item_name' => __( 'New Topic Name' ),
    'menu_name' => __( 'Topics' ),
  );    
 
// Now register the taxonomy
 
  register_taxonomy('topics',array('post'), array(
    'hierarchical' => true,
    'labels' => $labels,
    'show_ui' => true,
    'show_admin_column' => true,
    'query_var' => true,
    'rewrite' => array( 'slug' => 'topic' ),
  ));
 
}

Example 3: get taxonomies for custom post type

// get a list of available taxonomies for a post type
$taxonomies = get_taxonomies(['object_type' => ['your_post_type']])