Option to remove a post from a recurring event series in BE-Events-Calendar

remove-from-series.php

<?php
/**
 * Add the ability to remove a single event from a series with a checkbox (using CMB for metaboxes)
 * 
 * Uses Bill Erickon's BE-Events-Calendar, however this example uses Custom Metaboxes & Fields (CMB) for the events meta options
 * 
 * @author Joshua David Nelson
 */

// Remove event from series
add_action( 'updated_post_meta', 'jdn_remove_recurring_event', 10, 4 );
function remove_recurring_event( $meta_id, $post_id, $meta_key='', $meta_value='' ) {
	
	if( 'events' !== get_post_type( $post_id ) )
		return;
	
	// Change this condition based on the meta field type of your events calendar plugin
	$recurring_event = get_post_meta( $post_id, 'recurring_event', true );
	$remove_recurring_event = get_post_meta( $post_id, 'remove_recurring_event', true );
	
	if( $recurring_event && $remove_recurring_event == 'on' ) {
		
		// Remove the associated recurring event, and remove the meta option to remove the recurring event
		delete_post_meta( $post_id, 'recurring_event' );
		delete_post_meta( $post_id, 'remove_recurring_event' );
		
	}
	
}

show-meta-field-conditionally.php

<?php
/**
 * This creates a event metaboxes with CMB, as well as a checkbox to remove from a series,
 * 	only if the event is part of series (recurring event)
 * 
 * @author Joshua David Nelson
 */

/**
 * Override BE-Events-Calendar metaboxes
 * 
 * @link https://github.com/billerickson/BE-Events-Calendar/blob/master/be-events-calendar.php#L61
 */
add_filter( 'be_events_manager_metabox_override', 'jdn_override_events_metaboxes' );
function jdn_override_events_metaboxes( $metabox ) {
	return true;
}

/**
 * Initialize the metabox framework
 * 
 * @link https://github.com/WebDevStudios/Custom-Metaboxes-and-Fields-for-WordPress/wiki/Basic-Usage#initialize-metaboxes
 */
add_action( 'init', 'cmb_initialize_meta_boxes', 9999 );
function cmb_initialize_meta_boxes() {
    if ( !class_exists( 'cmb_Meta_Box' ) ) {
        require_once( 'lib/metabox/init.php' );
    }
}

// Add Custom Metaboxes
add_filter( 'cmb_meta_boxes', 'jdn_event_metaboxes' );
function jdn_event_metaboxes( $meta_boxes ) {

	$prefix = 'event_';
	
	$fields = array(
		array(
			'name' 	=> 'Event Host',
			'id'	=> $prefix . 'host',
			'desc'  => 'Optional',
			'type'	=> 'text_medium',
		),
		array(
			'name' 	=> 'Host Email Address',
			'id'	=> $prefix . 'host_email',
			'desc'  => 'Optional',
			'type'	=> 'text_email',
		),
		array(
			'name' 	=> 'Host Phone Number',
			'id'	=> $prefix . 'host_phone',
			'desc'  => 'Optional',
			'type'	=> 'text_medium',
		),
		array(
			'name' 	=> 'All Day Event',
			'id'	=> $prefix . 'all_day',
			'type'	=> 'checkbox',
		),
	    	array(
	    		'name' 	=> 'Event Start Date',
	    		'id'   	=> $prefix . 'start',
	    		'type' 	=> 'text_datetime_timestamp',
	    	),
	    	array(
	    		'name' 	=> 'Event End Date',
	    		'id'   	=> $prefix . 'end',
	    		'type' 	=> 'text_datetime_timestamp',
	    	),
	    	array(
	    		'name' 	=> 'Event Location',
	    		'id'   	=> $prefix . 'location',
	    		'type' 	=> 'address',
	    	),
    	);

	// Grab post id
	if( isset( $_GET['post'] ) ) {
		$post_id = $_GET['post'];
	} elseif( isset( $_POST['post_ID'] ) ) {
		$post_id = $_POST['post_ID'];
	}
	
	// Add option to remove from post series if the post is a recurring event, if there is a post id available
	if( isset( $post_id ) ) {
	    $recurring = get_post_meta( $post_id, 'recurring_event', true );
		if( !empty( $recurring ) && get_post_type( $post_id ) != 'recurring-events' ) {
	    	$fields[] = array(
				'name'    => 'Remove from Post Series',
				'id'      => 'remove_recurring_event',
				'type'    => 'checkbox',
				'desc'	  => 'Check to remove from recurring event series. Warning: Cannot be undone.',
			);
	     }
	} else {
		$post_id = null;
	}
	
	$event_metabox = array(
		'id'         => 'event_details',
		'title'      => 'Event Details',
		'pages'      => array( 'events', 'recurring-events' ), 
		'context'    => 'normal',
		'priority'   => 'high',
		'show_names' => true, 
		'fields'     => apply_filters( 'jdn_event_meta_fields', $fields, $post_id ), // allowing you to filter metabox fields
	);
	
	// Use this to override the metabox entirely and create your own
	$override = apply_filters( 'jdn_event_metabox_override', false );
	if ( false === $override ) $meta_boxes[ $event_metabox['id'] ] = $event_metabox;
	
	return $meta_boxes;
}