Taxonomy Models

Taxonomies follow the same pattern as post models, via \wpmvc\models\Taxonomy_Model. The extra piece is registry_object_type(), which returns the post types the taxonomy is attached to:

class Event_Category extends \wpmvc\models\Taxonomy_Model {

    public $taxonomy = 'event-category';

    public function registry() : array {
        return array(
            'hierarchical'      => true,
            'public'            => true,
            'show_ui'           => true,
            'show_admin_column' => true,
            'query_var'         => true,
            'show_in_rest'      => true,
        );
    }

    public function registry_labels() : array {
        return array(
            'name' => __( 'Event Category' ),
        );
    }

    public function registry_object_type() : array {
        return array( 'event' );
    }

}

Registering

Same as post types:

add_action( 'init', array( Event_Category::class, 'register' ) );

Querying posts by taxonomy

$events = Event::find()
    ->where_taxonomy( Event_Category::class, array( 'slug' => 'conferences' ) )
    ->all();