Ordering by multiple ACF fields - advanced-custom-fields

Question

I've seen a few questions similar to this but I still can't get things working so I thought I'd ask.
I have a Custom Post Type called 'Course'. This CPT has a custom field called 'date' which is either past, future or not set (null).
I am trying to write a query that hides the past courses, then shows future courses (ordered by date, soonest first) and then shows the courses where the date is not set (placeholder courses).
My plan was to add a 'placeholder_course' field to the course CPT and the date box would only appear if this was set to false. That way all of the placeholders would have a value of 1 for this field so I could sort by this to have them appear at then end, and then sort by the date to order the values in the date field correctly.
This is what I've been using:
<?php
$today = current_time('Ymd');
$args = array(
'post_type' => 'course',
'posts_per_page' => -1,
'meta_query' => array(
'relation' => 'OR',
'placeholder' => array(
'key' => 'placeholder_course',
'compare' => '=',
'value' => '1
),
'future_dates' => array(
'key' => 'date',
'compare' => '>=',
'value' => $today,
)
),
'orderby' => array(
'placeholder' => 'ASC',
'future_dates' => 'ASC',
),
);
?>
but the ordering is still coming out muddled. I'm pretty sure I've just done something wrong in the query, can anyone shed any light please?

Answer 1

Set up a true/false field for your placeholder value (if no date is set you can check on it) then the following code runs through either future dates or any post with the placeholder true/false value set to true
UPDATE: your'e probably gonna have to do this with 2 queries.
$args = array(
'post_type' => 'course',
'posts_per_page' => -1,
'meta_key' => 'date',
'meta_query' => array(
array(
'key' => 'date',
'value' => $today,
'compare' => '>=',
),
),
'orderby'=> 'meta_value_num',
'order' => 'ASC'
);
$args2 = array(
'post_type' => 'course',
'posts_per_page' => -1,
'meta_query' => array(
array(
'key' => 'placeholder_course',
'value' => true,
'compare' => '=',
),
),
'order' => 'ASC'
);