How to code a downloadable ICS file for an event

Question

On an events website I'd like to add a link to add an event to a vistors calendar. So when they are looking at the details of an event there would be a "Click to add to your calendar" button/link. I already generate/create an ICS file with all the events in it, but this would be just for the one specific event/entry. I'm thinking this would need to create a file on demand.

Answer 1

I'm done this using a custom controller action in a module that creates the ICS file on the fly and then sends it back as the response. This way, you can use a library to create the actual file – we're using the excellent spatie/icalendar-generator. This is a bit less error-prone and a bit easier to read, in my opinion. You can just use the public API of the library and don't have to worry about all the idiosyncrasies of the ICS format, since the library takes care of that.

Here's a simplified version of the controller endpoint we use for that purpose:

use Craft;
use craft\elements\Entry;
use craft\web\Controller;
use Spatie\IcalendarGenerator\Components\Calendar;
use Spatie\IcalendarGenerator\Components\Event;
use yii\web\NotFoundHttpException;
use yii\web\Response;

public function actionDownloadIcs(int $event): Response
{
    $entry = Entry::find()->id($event)->section('events')->one();

    if (!$entry) {
        throw new NotFoundHttpException('The requested event does not exist.');
    }

    $currentSite = Craft::$app->sites->currentSite;
    $calendar = Calendar::create($currentSite->name)
        ->productIdentifier($currentSite->getBaseUrl());

    $event = Event::create()
        ->name($entry->title)
        ->startsAt($entry->start_date)
        ->endsAt($entry->end_date)
        ->description($entry->description)
        ->address($entry->address)
        ->url($entry->getUrl());

    $calendar->event($event);

    return $this->response->sendContentAsFile(
        (string) $calendar,
        sprintf('%s-%s.ics', $entry->start_date->format('Y-m-d'), $entry->slug),
        ['mimeType' => 'text/calendar']
    );
}

Then you can output a link to that controller action in your templates:

<a href="{{ actionUrl('events/calendar/download-ics', { event: entry.id, }) }}">
    {{ 'Download event as ICS'|t }}
</a>

Note that the action path depends on the module ID, the name of the controller and the action.

Answer 2

No need to create an actual file - you can just use a Twig template as normal and send the appropriate headers to inform the browser what type of response you're sending. You need to be a bit careful with whitespace in the template if I recall correctly, so this code is deliberately not indented. Here's an example that I'm using in production:

{% apply spaceless %}
{% set entry = craft.entries.section('events').slug(craft.app.request.segments|last).one() %}
{% set startDate = entry.eventDate %}
{% header "Content-Type: text/calendar; charset=utf-8" %}
{% header "Content-Disposition: attachment; filename=calendar.ics" %}
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//{{ siteName }}//NONSGML v1.0//EN
X-WR-CALNAME:{{ entry.title }}
NAME:{{ entry.title }}
CALSCALE:GREGORIAN
BEGIN:VTIMEZONE
TZID:Europe/London
TZURL:http://tzurl.org/zoneinfo-outlook/Europe/London
X-LIC-LOCATION:Europe/London
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
TZNAME:BST
DTSTART:19700329T010000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
TZNAME:GMT
DTSTART:19701025T020000
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTAMP:{{ now|date("Ymd", "UTC") }}T{{ now|date("Hi", "UTC") }}00Z
UID:{{ entry.id }}@example.com
DTSTART;TZID=Europe/London:{{ startDate|date("Ymd", "UTC") }}T{{ startDate|date("Hi", "UTC") }}00
SUMMARY:{{ entry.title }}
URL:{{ entry.url }}
END:VEVENT
END:VCALENDAR
{% endapply %}

Answer 3

A really easy way to do it would be to use the (free) iCalendar plugin, which handles all of the annoying encoding / decoding for you:https://plugins.craftcms.com/icalendar