shortcode-render-tax-terms.php

<?php
/**
 * Shortcode: [pp_tax_list] to render an unlinked list of taxonomy terms assigned
 * to the current object.
 *
 * How to use: [pp_tax_list tax='<taxonomy>']
 * Optional params are:
 *      display='list|string' defaults to list
 *      wrapper_class='pp-tax-list' any css classes that are needed on the wrapper div.
 *
 * @param array $atts attributes for the shortcode function.
 * @param null $content there is no content for this shortcode.
 *
 * @return string|void
 */
function tax_to_list_shortcode( $atts, $content = null ) {

	/**
	 * Merge default attributes with the attributes provided in the shortcode.
	 */
	$attributes = shortcode_atts( [
		'tax' => 'category',
		'display' => 'list',
		'wrapper_class' => 'pp-tax-list',
	], $atts );

	/**
	 * Bail silently if we don't have a working taxonomy.
	 */
	if ( ! taxonomy_exists( $attributes['tax'] ) ) {
		return;
	}

	/**
	 * Get the object ID for the current post type.
	 */
	$object_id = get_the_ID();

	/**
	 * Get the post type of the current object.
	 */
	$object_type = get_post_type( $object_id );

	/*
	 * Setup fallback message when no terms exists for this object ID.
	 */
	$terms_output = "There are no terms in {$attributes['tax']} for {$object_type} with ID {$object_id}";

	/**
	 * Get the actual terms for the object and taxonomy.
	 */
	$terms = get_the_terms( $object_id, $attributes['tax'] );

	/**
	 * Only prepare rendering if we have terms.
	 */
	if ( ! is_a( $terms, 'WP_Error' ) && false !== $terms ) {

		switch ( $attributes['display'] ) {
			case 'string':
				$terms_output = join( ', ', wp_list_pluck( $terms, 'name' ) );
				break;
			case 'list':
			default:
				$terms_output = '<ul><li>' . join( '</li><li>', wp_list_pluck( $terms, 'name' ) ) . '</li></ul>';
				break;
		}

	}

	$output_start = "<div class='{$attributes['wrapper_class']}'>";
	$output_end = "</div>";

	return $output_start . $terms_output . $output_end;
}

add_shortcode( 'pp_tax_list', 'tax_to_list_shortcode' );