Why does wp_query only display the most recent post when using order ASC?

Question

Problem: I want to list posts of a category, displaying those with custom-field 'start-date' after today (in the future) with order ASC. When this is done, I want to display all those with start-date before today (in the past) with order DESC.

The second list is no problem.

But the first list only displays the single most recent post when I use order => 'ASC'. If I use order => 'DESC', all the posts display correctly.

Where do I fail in this code?

    $args = array(
                        'cat' => $cat_id,
                        'meta_key' => 'dato-start',
                        'orderby' => 'meta_value_num',
                        'order' => 'ASC',
                        'paged' => $paged
                    );
                    
    $arrangementer = new WP_Query($args);
    if ( $arrangementer->have_posts() ) :
       while ( $arrangementer->have_posts() ) : $arrangementer->the_post();

            $today = date('Ymd');
            $unnagjort = FALSE;
            $startDato = get_post_meta(get_the_ID(), 'dato-start', TRUE);
            $sluttDato = get_post_meta(get_the_ID(), 'dato-slutt', TRUE);;


            if ( get_field('dato-start') && ($today > $startDato) ) $unnagjort = TRUE;          
                
            if (!$unnagjort)    {
                get_template_part( 'template-parts/content', get_post_format() );
            }

            endwhile;

Then I run rewind_posts() and the same query, but order DESC, and filter out those with $unnagjort == TRUE.

The first query returns only the most recent requested post, the second returns all the requested posts.

Answer 1

There are 3 problems here

It's Using a Non-Standard Date Format

The dates are being stored like this:

20230131

Which is ok for us as we can interpret that as a date with no spaces, but it needs to stored like this:

2023 01 31

Specifically, it needs to be timestamp like this:

YYYY-MM-DD HH:MM:SS

or this:

YYYY-MM-DD

You can choose a different separator, and there is some flexibility over how the date is formatted, e.g. YY/MM/DD also works, as does Y-M-D, as long as the year comes before the month, and the month comes before the day.

You will need to convert all your existing data to use a consistent timestamp format.

It Does Not Use Date Based Ordering

Once the above change has been made, the date oriented options become available, e.g. you could do this:

$args = [
    'meta_query' => [
        [
            'key'     => 'release_date',
            'value'   =>  array( '2019-01-01', '2019-12-31' ),
            'type'    =>  'date',
            'compare' =>  'between'   
        ]
    ]
];
 
$query = new WP_Query($args);

This also means you could do:

$args = [
    'meta_key'  => 'release_date',
    'meta_type' => 'DATE',
    'orderby'   => 'meta_value',
];
 
$query = new WP_Query($args);

The Loop Check

In the main loop there is this code:

            if ( get_field('dato-start') && ($today > $startDato) ) $unnagjort = TRUE;          
                
            if (!$unnagjort)    {
                get_template_part( 'template-parts/content', get_post_format() );
            }

You've assumed because only 1 post is shown that the WP_Query parameters are wrong, but actually, it's more likely because of this check. If it fetches 10 posts but $unnagjort is only false once, it will show 1 post, how would you tell this apart from it fetching a single post? Even if there are more posts, it will only return them 10 or so at a time!

Instead, add a meta_query to WP_Query and make that do the work of filtering them out instead of doing it in PHP. Ask for all posts that have a start date earlier than today, for example:

$args = [
    'meta_query' => [
        [
            'key'     => 'release_date',
            'value'   =>  date('Y-M-D');,
            'type'    =>  'date',
            'compare' =>  '<'   
        ]
    ]
];

Then your if check can be eliminated, and it will only return the posts you want