Ordering Wordpress posts by multiple meta values - php

Question

Using get_posts(), I need to first retrieve posts that fall on a certain day (the day is set by a custom field - just the date, not time). I do this by using a meta key/value. Then, I need to order these posts based on the time of day (which is a separate custom field, just time, not date). So essentially I need to pull in all the events that fall on a given day, and order them according to the time.
First I grab the day, using a custom field:
if ( get_field('festival_day') ) {
$day_stamp = get_field('festival_day');
}
Then I set my arguments for the query:
$args = array(
'posts_per_page' => -1,
'post_type' => 'event',
'meta_key' => 'event_date',
'meta_value' => $day_stamp
);
$events = get_posts( $args );
So.. the question is, how do I query the other custom field (which is the start time), and then sort by that time? The time field key is event_start_time.
Thanks!

Answer 1

You can user WP_Query to retrieve your events and you can query it something like below:
$args = array(
'post_type' => 'event',
'order' => 'DESC',
'orderby' => 'meta_value',
'meta_key' => 'event_start_time',
'meta_query' => array(
array(
'key' => 'event_start_time',
'value' => 'yourValue_here',
'compare' => '>='
),
array(
'key' => 'event_date',
'value' => $day_stamp,
'compare' => '='
)
)
);
$query = new WP_Query( $args );
UNTESTED but it should work.

Answer 2

Check this code, it should work to sort your post according to time from resulting post of day.
$args = array(
'post_type' => 'post',
'posts_per_page' => -1,
'meta_key' => 'event_start_time',
'orderby' => 'meta_value_num',
'order' => 'ASC',
'meta_query'=> array(
array(
'key' => 'event_date',
'value' => $day_stamp,
'compare' => 'IN'
)
)
);
$the_query = new WP_Query( $args );
if ( $the_query->have_posts() ) {
echo '<ul>';
while ( $the_query->have_posts() ) {
$the_query->the_post();
echo '<li>'. get_the_title().'</li>';
}
echo '</ul>';
} else {
// no posts found
}