Cannot able to create all day .ics event - php

Question

I am creating an .ics file for outlook calendar, It is working properly when i pass start_time and end_time of event to it but i'm not able to work on all day event. Should i pass 000000 to time for eg. 20190703T000000.
I am passing date time of event like this :
$eventArray[]=array('description'=>'Event','dtstart' => $eventList->date.'T'.$eventList->start_time,'dtend' => $eventList->date.'T'.$eventList->end_time);
Library for icsevent:
<?php
Class Icsevents {
const DT_FORMAT = 'Ymd\THis'; //define date format here
public $events;
public function __construct($events) {
if(count($events)>0) {
for($p=0;$p<=count($events)-1;$p++) {
foreach($events[$p] as $key => $val) {
$events[$p][$key] = $this->sanitize_val($val, $key);
}
}
}
$this->events=$events;
}
private function sanitize_val($val, $key = false) {
switch($key) {
case 'dtend':
case 'dtstamp':
case 'dtstart':
$val = $this->format_timestamp($val);
break;
default:
$val = $this->escape_string($val);
}
return $val;
}
private function format_timestamp($timestamp) {
$dt = new DateTime($timestamp);
return $dt->format(self::DT_FORMAT);
}
private function escape_string($str) {
return preg_replace('/([,;])/','$1', $str);
}
function prepare() {
$cp=array();
if(count($this->events)>0) {
$cp[]= 'BEGIN:VCALENDAR';
$cp[]= 'VERSION:2.0';
$cp[]= 'PRODID:-//hacksw/handcal//NONSGML v1.0//EN//b3';
$cp[]= 'CALSCALE:GREGORIAN';
for($p=0;$p<=count($this->events)-1;$p++) {
$cp[]='BEGIN:VEVENT';
foreach($this->events[$p] as $key => $val) {
if ( $key === 'url' ) {
$cp[]= 'URL;VALUE=URI:'.$val;
} elseif ( $key === 'alarm' ) {
$cp[] = 'BEGIN:VALARM';
$cp[] = 'TRIGGER:-PT' . $val;
$cp[] = 'ACTION:DISPLAY';
$cp[] = 'END:VALARM';
} elseif ( $key === 'dtstart' || $key === 'dtend' ) {
$cp[]= strtoupper($key).';TZID=Asia/Kolkata:'.$val;
} else {
$cp[]= strtoupper($key).':'.$val;
}
}
$cp[]= 'END:VEVENT';
}
$cp[]='END:VCALENDAR';
}
return implode("\r\n", $cp);
}
}

Answer 1

You want to use the DATE format defined in https://www.rfc-editor.org/rfc/rfc5545#section-3.3.4
You can either choose to provide only a DTSTART:
DTSTART;VALUE=DATE:20190703
or, if the allay event last for a longe period of time, provide both DTSTART and DTEND using that same format:
DTSTART;VALUE=DATE:20190703
DTEND;VALUE=DATE:20190712
See also https://devguide.calconnect.org/Handling-Dates-and-Times/