我希望本机WordPress搜索输入除了标准标题和内容搜索之外，还可以搜索元数据，但是设置meta_query 添加AND 当我需要的是OR.

我的职能：

function search_faqs_metadata($query) {
  if(!is_admin() && $query->is_main_query()) {
    if($query->is_search) {
      $query->set(\'meta_query\', array(array(
        \'key\' => \'_faqs\',
        \'value\' => $query->query_vars[\'s\'],
        \'compare\' => \'LIKE\'
      )));
    }
  }
}
add_action(\'pre_get_posts\', \'search_faqs_metadata\');

问题是它生成的查询：

SELECT SQL_CALC_FOUND_ROWS wp_posts.ID FROM wp_posts
INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id)
WHERE 1=1
AND (
  (
    (wp_posts.post_title LIKE \'%foobar%\') OR (wp_posts.post_content LIKE \'%foobar%\')
  )
)
AND (wp_posts.post_password = \'\')
AND wp_posts.post_type IN (\'post\', \'page\', \'attachment\')
AND (wp_posts.post_status = \'publish\')
AND (  //I need this to be an OR!
  (wp_postmeta.meta_key = \'_faqs\' AND CAST(wp_postmeta.meta_value AS CHAR) LIKE \'%foobar%\')
)
GROUP BY wp_posts.ID
ORDER BY wp_posts.post_title LIKE \'%foobar%\' DESC, wp_posts.post_date DESC LIMIT 0, 10

因此，除非帖子标题/内容AND 元数据与搜索词匹配。

我知道有一个relation 的参数meta_query 但它仅在比较多个元数据值时有效。

目前我正在跑步str_replace() 在最后一个查询上更改最后一个AND 变成一个OR. 我选择这种方法是因为，虽然有黑客行为，但它依赖于我需要添加多少代码才能成功进行调整：

function search_where_or_metadata($where) {
  if(is_search()) {
    global $wp_query;
    $new_where = $where;
    $new_where = str_replace(\'AND ( (wp_postmeta.meta_key\', \'OR ( (wp_postmeta.meta_key\', $where);
    return $new_where;
  }
  return $where;
}
add_filter(\'posts_where\', \'search_where_or_metadata\');

EDIT下面是一个更好的函数，它使用更合适的过滤器来更改AND 到OR:

function change_meta_key_where_from_and_to_or($sql) {
  if(is_search()) {
    $sql[\'where\'] = substr($sql[\'where\'], 1, 3) == \'AND\' ? substr_replace($sql[\'where\'], \'OR\', 1, 3) : $sql[\'where\'];
  }
  return $sql;
}
add_filter(\'get_meta_sql\', \'change_meta_key_where_from_and_to_or\');

有没有更好的办法改变决赛AND 变成一个OR?

function search_faqs_metadata($query) {
  if(!is_admin() && $query->is_main_query()) {
    if($query->is_search) {
      $query->set(\'meta_query\', array(array(
        \'key\' => \'_faqs\',
        \'value\' => $query->query_vars[\'s\'],
        \'compare\' => \'LIKE\'
      )));
    }
  }
}
add_action(\'pre_get_posts\', \'search_faqs_metadata\');

function change_meta_key_where_from_and_to_or($sql) {
  if(is_search()) {
    $sql[\'where\'] = substr($sql[\'where\'], 1, 3) == \'AND\' ? substr_replace($sql[\'where\'], \'OR\', 1, 3) : $sql[\'where\'];
  }
  return $sql;
}
add_filter(\'get_meta_sql\', \'change_meta_key_where_from_and_to_or\');

function wpse143477_parse_clauses($clauses, $query) {
    if(!is_admin() && $query->is_main_query()) {
        if($query->is_search) {
            $keyword = $query->get(\'s\');
            $keyword = \'%\' . like_escape( $keyword ) . \'%\';
            $post_ids = $wpdb->get_col( $wpdb->prepare( "
                SELECT DISTINCT post_id FROM {$wpdb->postmeta}
                WHERE meta_key = \'_faqs\' AND meta_value LIKE \'%s\'
            ", $keyword ) );
            if( !empty( $post_ids )) {
                $clauses[\'where\'] .= " OR {$wpdb->posts}.ID IN (" . implode( \', \', $post_ids ) . \')\';
            }
        }
    }

    return $clauses;
}
add_filter( \'posts_clauses\', \'wpse143477_parse_clauses\', 10, 2 );