Loop through posts of a custom-post-type (event) and create .ics (iCal) file?

2 comments

1. This is entirely based on Event Organiser (a plug-in I’ve developed). The code is lifted almost straight from the source but with alterations. As such I’ve not tested the code as given.

   Step 1: Create a feed

   This is simple:

   add_action('init','wpse63611_add_events_feed');
   function wpse63611_add_events_feed(){
        add_feed('my-events','wpse63611_events_feed_output');
   }
   

   This adds a feed to your site: www.site.com?feed=my-events or www.site.com/feed/my-events if you have pretty permalinks. The wpse63611_events_feed_output() callback will output the contents of the ICAL file. But first…

   Step 2: Alter the query

   WordPress doesn’t know what this feed is meant to contain. Here we use the pre_get_posts to tell WordPress, that for this feed we want posts of post type ‘wr_event’. We could get events from a particular category, venue or between certain dates too.

   By separating out the query from the output, you can have multiple feeds which use the same output function – but query different events (based on time, location, category etc).

   add_action( 'pre_get_posts', 'wpse63611_event_feed_query' );
   function wpse63611_event_feed_query( $query ) {
   
        $yesterday = current_time('timestamp') - 24*60*60;
        $compare = $latest ? '>' : '<';
   
        if( $query->is_feed('eo-events') ){
            $query->set('post_type', 'wr_event');
            $query->set('posts_per_page', -1);
            $query->set('meta_key', 'event_date');
            $query->set('orderby', 'meta_value_num');
            $query->set('order', 'ASC');
            $query->set('meta_compare', $compare);
            $query->set('meta_value', $value);
        }
   }
   

   Step 3: The contents of the ICS file

   As mentioned earlier, wpse63611_events_feed_output() is responsible for printing the output of our feed.

    function wpse63611_events_feed_output(){
         //Let's give it a name;
         $filename = urlencode( 'my_events' . date('Y-m-d') . '.ics' );
   
         //Collect output 
         ob_start();
   
         // File header
         header( 'Content-Description: File Transfer' );
         header( 'Content-Disposition: attachment; filename=' . $filename );
         header('Content-type: text/calendar');
         header("Pragma: 0");
         header("Expires: 0");
   ?>
   BEGIN:VCALENDAR
   VERSION:2.0
   PRODID:-//<?php  get_bloginfo('name'); ?>//NONSGML Events //EN
   CALSCALE:GREGORIAN
   X-WR-CALNAME:<?php echo get_bloginfo('name');?> - Events
   
   <?php
   
       // Loop through events
       if ( have_posts() ):
   
            $now = new DateTime();
            $datestamp =$now->format('YmdTHisZ');
   
            while( have_posts() ): the_post();
                 global $post;
   
                 $uid = md5(uniqid(mt_rand(), true))."@mysite.com";
   
                 $start = unixToiCal(get_event_date($post), get_event_time($post));
                 $end = unixToiCal(get_event_end_date($post), get_event_end_time($post));
   
                 $summary = wpse63611_escape_icalText(get_the_title())
                 $description = apply_filters('the_excerpt_rss',  get_the_content());
                 $description = wpse63611_escape_icalText($description);
   
   BEGIN:VEVENT
   UID:<?php echo $uid;?>
   
   DTSTAMP:<?php echo $datestamp;?>
   
   DTSTART:<?php echo $start; ?>
   
   DTEND:<?php echo $end; ?>
   
   SUMMARY:<?php echo wpse63611_esc_ical_text($summary);?>
   
   DESCRIPTION:<?php echo wpse63611_esc_ical_text($description);?>
   
   END:VEVENT
   
            endwhile;
   
       endif;
   ?>
   END:VCALENDAR
   <?php
   
       //Collect output and echo 
       $eventsical = ob_get_contents();
       ob_end_clean();
       echo $eventsical;
       exit();
   }   
   

   I’ve used the unixToiCal function you’ve defined in your question. I’ve also used the following to remove anything that might upset an ICAL parser:

    function wpse63611_esc_ical_text( $text='' ){
   
       $text = str_replace("", "", $text);
       $text = str_replace(",", ",", $text);
       $text = str_replace(";", ";", $text);
       $text = str_replace("n", "n ", $text);
   
       return $text;
    }
   

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2. Try this:

   First add this functions to your theme’s functions.php

   //this will call the download function if needed
   function Ical_download() {
       global $wp;
       global $wp_query;
       if (isset($wp->query_vars["ical_download"])){
           event_list_iCal();
           exit();
       }
   }
   
   add_action('template_redirect', 'Ical_download');
   
   
   //this will add ical_download to the list of query vars
   function ical_download_query_val() {
       global $wp;
       $wp->add_query_var('ical_download');
   }
   
   add_filter('init', 'ical_download_query_val');
   function event_list_iCal( $latest = true ) {
   
       $yesterday = time() - 24*60*60;
       $compare = $latest ? '>' : '<';
   
       $args = array(
           'post_type' => 'wr_event',
           'posts_per_page' => -1, // show all posts
           'meta_key' => 'event_date',
           'orderby' => 'meta_value_num',
           'order' => 'ASC',
           'meta_value' => $yesterday,
           'meta_compare' => $compare,
       );
   
       $loop = new WP_Query( $args );
       $ical = "BEGIN:VCALENDAR
   VERSION:2.0
   PRODID:-//hacksw/handcal//NONSGML v1.0//EN
   ";
       while ( $loop->have_posts() ) : $loop->the_post();
   
       $ical .= "BEGIN:VEVENT
   UID:" . md5(uniqid(mt_rand(), true)) . "example.com
   DTSTAMP:" . gmdate('Ymd').'T'. gmdate('His') . "Z
   DTSTART:".get_event_date($post)."00Z
   DTEND:".get_event_end_date($post);."00Z
   SUMMARY:".$post->title."
   DESCRIPTION:".$post->content."
   END:VEVENT
   ";
   
       endwhile;
   
       $ical .= "END:VCALENDAR";
   
       //set correct content-type-header
       header('Content-type: text/calendar; charset=utf-8');
       header('Content-Disposition: inline; filename=calendar.ics');
       echo $ical;
       exit;
   
   }
   

   So just update the summery and description fields as well as the start and end times to the right format and your download link should be something like:

   <a href="<?php echo get_bloginfo('url').'?ical_download';?>">Download iCal</a>
   

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