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<?php 

/*------------------------------------*\
	Custom Post Type
\*------------------------------------*/

/* register */

function products_cpt() {
    register_post_type( 'products', array( 
		'labels' => array('name' => 'Models','singular_name' => 'Model',),
		'rewrite' => array( 'slug' => 'product' ),
      	'public' => true,
      	'menu_position' => 20,
      	'menu_icon' => 'dashicons-cart',
      	'supports' => array( 'title', 'editor', 'author', 'custom-fields', 'thumbnail' ),
		'publicly_queryable' => 'true',
		'query_var' => true
    ));
}

add_action( 'init', 'products_cpt' );

register_taxonomy(
    'product_categories',
    'products',
    array(
        'hierarchical' => true,
        'label' => 'Categories',
        'query_var' => true,
        'rewrite' => true
    )
);

/* allow filtering in WP backend */

/**
 * Display a custom taxonomy dropdown in admin
 * @author Mike Hemberger
 * @link http://thestizmedia.com/custom-post-type-filter-admin-custom-taxonomy/
 */

function tsm_filter_post_type_by_taxonomy() {
	global $typenow;
	$post_type = 'products'; // change to your post type
	$taxonomy  = 'product_categories'; // change to your taxonomy
	if ($typenow == $post_type) {
		$selected      = isset($_GET[$taxonomy]) ? $_GET[$taxonomy] : '';
		$info_taxonomy = get_taxonomy($taxonomy);
		wp_dropdown_categories(array(
			'show_option_all' => __("Show All {$info_taxonomy->label}"),
			'taxonomy'        => $taxonomy,
			'name'            => $taxonomy,
			'orderby'         => 'name',
			'selected'        => $selected,
			'show_count'      => true,
			'hide_empty'      => false,
			'value_field' 	  => 'slug',
			'hierarchical' => 1
		));
	};
}
add_action('restrict_manage_posts', 'tsm_filter_post_type_by_taxonomy');

?>