metaboxes.php

<?php
// Exit if accessed directly
defined( 'ABSPATH' ) || exit;
/** Walker_Category_Checklist class */
require_once( ABSPATH . 'wp-admin/includes/class-walker-category-checklist.php' );
/**
 * Extends Walker_Category_Checklist and uses radio input instead of checklist
 *
 * @since 0.4.1
 */
class WP_Event_Calendar_Walker_Category_Radio extends Walker_Category_Checklist {
	/**
	 * Start the element output.
	 *
	 * @see Walker::start_el()
	 *
	 * @since 0.4.1
	 *
	 * @param string $output   Passed by reference. Used to append additional content.
	 * @param object $category The current term object.
	 * @param int    $depth    Depth of the term in reference to parents. Default 0.
	 * @param array  $args     An array of arguments. @see wp_terms_checklist()
	 * @param int    $id       ID of the current term.
	 */
	public function start_el( &$output, $category, $depth = 0, $args = array(), $id = 0 ) {
		// Note that Walker classes are trusting with their previously
		// validated object properties.
		$taxonomy = $args['taxonomy'];
		$name     = 'tax_input[' . $taxonomy . ']';
		// Maybe show popular categories tab
		$args['popular_cats'] = empty( $args['popular_cats'] )
			? array()
			: $args['popular_cats'];
		// Maybe add popular category class
		$class = in_array( $category->term_id, $args['popular_cats'] )
			? ' class="popular-category"'
			: '';
		// Maybe use already selected categories
		$args['selected_cats'] = empty( $args['selected_cats'] )
			? array()
			: $args['selected_cats'];
		/** This filter is documented in wp-includes/category-template.php */
		$output .= "\n<li id='{$taxonomy}-{$category->term_id}'$class>" .
			'<label class="selectit"><input value="' . $category->name . '" type="radio" name="' . $name . '[]" id="in-' . $taxonomy . '-' . $category->term_id . '"' .
			checked( in_array( $category->term_id, $args['selected_cats'] ), true, false ) .
			disabled( empty( $args['disabled'] ), false, false ) . ' /> ' .
			esc_html( apply_filters( 'the_category', $category->name ) ) . '</label>';
	}
}
/**
 * Event Types Metabox
 * Output radio buttons instead of the default WordPress mechanism
 *
 * @since 0.4.1
 *
 * @param array  $args
 * @param string $taxonomy
 *
 * @return array
 */
function wp_event_calendar_taxonomy_args( $args = array(), $taxonomy = '' ) {
	if ( 'event-type' === $taxonomy ) {
		$r = apply_filters( 'wp_event_calendar_taxonomy_args', array(
			'meta_box_cb' => 'post_categories_meta_box'
		), $args );
		$args = wp_parse_args( $args, $r );
	}
	return $args;
}
/**
 * Use the custom walker for radio buttons
 *
 * @since 0.4.1
 *
 * @param array $args
 *
 * @return array
 */
function wp_event_calendar_checklist_args( $args = array() ) {
	if ( 'event-type' === $args['taxonomy'] ) {
		$r = apply_filters( 'wp_event_calendar_checklist_args', array(
			'walker' => new WP_Event_Calendar_Walker_Category_Radio(),
		), $args );
		$args = wp_parse_args( $args, $r );
	}
	return $args;
}