I want to order categories based upon the latest post time

Question

For example if category A has post 1 which is created yesterday and category B has post 2 which is created today. So, the category will be listed in order Category B Category A

Have anyone implemented this before?

Answer 1

This code list all parent categories on the basis of recent publish post in that category.

function ravs_cat_list(){

    /* all parent categories*/
    $args = array(
            'parent' => 0
        );
    $cats = get_categories( $args );

    /* get recent post from each category */
    foreach( $cats as $cat ):
        $args = array(
                'numberposts' => 1,
                'category' => $cat->term_id
            );
        $recent_posts = wp_get_recent_posts( $args );
        /* category list */
        $cat_list[]=array(
                'id' => $cat->term_id,
                'name' => $cat->name,
                'post_date' => $recent_posts[0]['post_date']
            );
    endforeach;

    /* sort $cat_list on basis of resent publish post */
    function sortFunction( $a, $b ){
        return strtotime($a["post_date"]) - strtotime($b["post_date"]) > 1 ? -1 : 1;
    }
    usort($cat_list, "sortFunction");

    /* print list of sorted categories */
    echo'<ul class="cat-list">';
    foreach ($cat_list as $cat):
    ?>
    <li><?php print_r($cat['name']); ?></li>
    <?php
    endforeach;
    echo '</ul>';
}

Answer 2

Try it:

function get_sorted_categories( $order_by = 'id' ){
    global $wpdb;

    $category = get_categories();

    $order = [
        'id' => 'post.ID',
        'date' => 'post.post_date',
        'modified' => 'post.post_modified',
    ];

    $order_by = $order[ $order_by ];

    $q = $wpdb->get_results("SELECT tax.term_id FROM `{$wpdb->prefix}term_taxonomy` tax
    INNER JOIN `{$wpdb->prefix}term_relationships` rel ON rel.term_taxonomy_id = tax.term_id
    INNER JOIN `{$wpdb->prefix}posts` post ON rel.object_id = post.ID WHERE tax.taxonomy = 'category' AND post.post_type = 'post' AND post.post_status = 'publish' ORDER BY {$order_by} DESC");

    $sort = array_flip( array_unique( wp_list_pluck( $q, 'term_id' ) ) );

    usort( $category, function( $a, $b ) use ( $sort, $category ) {
        if( isset( $sort[ $a->term_id ], $sort[ $b->term_id ] ) && $sort[ $a->term_id ] != $sort[ $b->term_id ] )
            $res = ($sort[ $a->term_id ] > $sort[ $b->term_id ]) ? 1 : -1;
        else if( !isset( $sort[ $a->term_id ] ) && isset( $sort[ $b->term_id ] ) )
            $res = 1;
        else if( isset( $sort[ $a->term_id ] ) && !isset( $sort[ $b->term_id ] ) )
            $res = -1;
        else
            $res = 0;

        return $res;
    } );

    return $category;
}

print_r( get_sorted_categories() );
print_r( get_sorted_categories('date') );
print_r( get_sorted_categories('modified') );

Get categories order by (post ID | post date | post modified date). Without any loop and fast!