/icalendar

Library for reading and writing iCalendar files in PHP

Primary LanguagePHP

Zap Calendar iCalendar Library

(https://github.com/zcontent/icalendar)

The Zap Calendar iCalendar Library is a PHP library for supporting the iCalendar (RFC 5545) standard.

This PHP library is for reading and writing iCalendar formatted feeds and files. Features of the library include:

  • Read AND write support for iCalendar files
  • Object based creation and manipulation of iCalendar files
  • Supports expansion of RRULE to a list of repeating dates
  • Supports adding timezone info to iCalendar file

All iCalendar data is stored in a PHP object tree. This allows any property to be added to the iCalendar feed without requiring specialized library function calls. With power comes responsibility. Missing or invalid properties can cause the resulting iCalendar file to be invalid. Visit iCalendar.org to view valid properties and test your feed using the site's iCalendar validator tool.

See the examples folder for programs that read and write iCalendar files. At its simpliest, you need to include the library at the top of your program:

require_once($path_to_library . "/zapcallib.php");

Create an ical object using the ZCiCal object:

$icalobj = new ZCiCal();

Add an event object:

$eventobj = new ZCiCalNode("VEVENT", $icalobj->curnode);

Add a start and end date to the event:

// add start date
$eventobj->addNode(new ZCiCalDataNode("DTSTART:" . ZCiCal::fromSqlDateTime("2020-01-01 12:00:00")));

// add end date
$eventobj->addNode(new ZCiCalDataNode("DTEND:" . ZCiCal::fromSqlDateTime("2020-01-01 13:00:00")));

Write the object in iCalendar format using the export() function call:

echo $icalobj->export();

This example will not validate since it is missing some required elements. Look at the simpleevent.php example for the minimum # of elements needed for a validated iCalendar file.

To read an existing iCalendar file/feed, create the ZCiCal object with a string representing the contents of the iCalendar file:

$icalobj = new ZCiCal($icalstring);

Known Limitations

  • Since the library utilizes objects to read and write iCalendar data, the size of the iCalendar data is limited to the amount of available memory on the machine. The ZCiCal() object supports reading a range of events to minimize memory space.
  • The library ignores timezone info when importing files, instead utilizing PHP's timezone library for calculations (timezones are supported when exporting files). Imported timezones need to be aliased to a PHP supported timezone.
  • At this time, the library does not support the "BYSETPOS" option in RRULE items.
  • At this time, the maximum date supported is 2036 to avoid date math issues with 32 bit systems.
  • Repeating events are limited to a maximum of 5,000 dates to avoid memory or infinite loop issues