Convert ISOdate to phpdate for ACF custom field query - php

Question

I've built a custom beaver builder (wordpress) module. I'm fetching posts via Ajax. I need to query posts based off an ACF custom field date.
I am posting the date in ISO8601 format (eg 2013-12-01T00:00:00-05:00). Server side, I grab the start and end. I convert them into the format needed for the ACF query https://www.advancedcustomfields.com/resources/date-picker/
$start_date = date('Ymd', strtotime($_POST['start']));
$end_date = date('Ymd', strtotime($_POST['end']));
I run the query, and get nothing. I echo the string out, and they look correct.
If I set the date as per the example in the ACF docs - it works (code below). So I must be converting the ISOdate $_POST['start'] incorrectly. How do I convert the ISODATE so that is it something that I can use in the query?
function get_ajax_event_calendar_posts() {
$today = date('Ymd'); // this works...
$args = array(
'post_type' => array('event'),
'meta_query' => array(
array(
'key' => 'start_date',
'compare' => '<=',
'value' => $today,
),
array(
'key' => 'end_date',
'compare' => '>=',
'value' => $today,
)
),
'post_status' => array('publish'),
'posts_per_page' => 100,
'nopaging' => true,
'order' => 'DESC',
'orderby' => 'date'
);
// The Query
$ajaxposts = get_posts( $args );
//... etc
}
** edit **
.... the date stuff wasn't the problem. I was the problem... switched my compares round the right way and all works...

Answer 1

You haven't said what format you actually need to store the data, however you did say date('Ymd') works. Either way, use the DateTime class:
<?php
$x = new DateTime('2013-12-01T00:00:00-05:00');
echo $x->format('d/m/Y H:i:s') . "\n"; // 01/12/2013 00:00:00
echo $x->format('dmY') . "\n"; // 01122013
Here are the date formats https://www.php.net/manual/en/function.date.php