如何正确使用`POSTS_DISTIFICT`？

我浏览了互联网，但找不到一个好的工作示例或关于过滤器的讨论posts_distinct 我正在使用高级自定义字段，但我认为这可能不是问题所在。不管怎样，我尝试的都不管用。

我的函数调用是否正确？还是在WP\\u查询之前

//functions.php
function search_distinct() { 
    return "DISTINCT"; 
}
add_filter(\'posts_distinct\', \'search_distinct\');

//archive.php
<?php
    $args = array(
       \'post_type\' => \'homily\',
       \'posts_per_page\' => -1,
       \'meta_key\' => \'homilist\',
       \'orderby\' => \'meta_value\', 
       \'order\' => \'ASC\'
    );
    $the_query = new WP_Query( $args );

    search_distinct(); //Correct?

    if ( $the_query->have_posts() ) {
       echo \'<ul>\';
           while ( $the_query->have_posts() ) {
              $the_query->the_post();
                    echo \'<li>\' .the_field(\'homilist\') . \'</li>\';
                }
        echo \'</ul>\';
     }
     wp_reset_postdata(); ?>

Update:最终得到的WordPress式解决方案比我所希望的要少，尽管有善意的建议：

<?php
    global $wpdb;
    $querystr = "SELECT DISTINCT meta_value 
                FROM $wpdb->postmeta 
                WHERE meta_key = \'homilist\' 
                ORDER BY meta_value ASC";
    $homilists = $wpdb->get_results( $querystr, OBJECT);

    echo \'<select id="homilist">\';
    for ($i = 1; $i < count($homilists); $i++) {
        echo \'<option value="\'.$homilists[$i]->meta_value.\'">\'.$homilists[$i]->meta_value.\'</option>\';
    }
    echo \'</select>\'; 
?>

// functions.php // Used as a filter for archive.php to eliminate duplicate posts function search_distinct() { return "DISTINCT"; } //archive.php <?php $args = array( \'post_type\' => \'homily\', \'posts_per_page\' => -1, \'meta_key\' => \'homilist\', \'orderby\' => \'meta_value\', \'order\' => \'ASC\' ); // Get posts, make them distinct. search_distinct is defined in functions.php add_filter(\'posts_distinct\', \'search_distinct\'); $the_query = new WP_Query( $args ); remove_filter(\'posts_distinct\', \'search_distinct\'); if ( $the_query->have_posts() ) { echo \'<ul>\'; while ( $the_query->have_posts() ) { $the_query->the_post(); echo \'<li>\' .the_field(\'homilist\') . \'</li>\'; } echo \'</ul>\'; } wp_reset_postdata(); ?>

小码农CODE

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