编辑3-根据G.M.的建议进行修订。代码运行时无错误，但相邻的后过滤器仍不过滤。代码注释中注意到的更改，帖子底部注意到的当前问题

编辑2-反映以下G.M.的代码建议。我对修改后的join/where-filter函数应该放在哪里感到困惑，所以我添加了更多的mu-plugin代码结构

编辑1-反映了凯撒在下面的评论，提供了示例。此外，我还错误地知道是哪种代码过滤了我的帖子。问题与Members插件无关

我有一个mu插件过滤我的WP查询，这样在索引循环中，访问者只能看到他们可以阅读的帖子。它通过为帖子作者提供为每个帖子分配多级成员分类的能力来实现这一点。

在最低（公共）级别，该职位没有附加任何成员分类。

以下是mu插件中的查询过滤器：

if ( ! class_exists ( \'Site_Members_Taxonomy\' ) ) {

class Site_Members_Taxonomy
{
    //define( \'LANG\', \'some_textdomain\' ); deleted LANG, was throwing errors

    public $post_types = array( \'post\', \'page\', \'gallery\' );
    public $tax = \'membership\';
    public $tax_label; // CHANGE: made these three vars public

    public function __construct()
    {
    $this->tax_label = __( \'Membership\' );

    // plugin defines taxonomy and membership meta and then:

    add_action( \'pre_get_posts\', array( &$this, \'filter_query\' ) );

    /**
     * Modify the query based on membership taxonomy
     */
    function filter_query( $query ) {

        //quit right now if in admin
        if( is_admin() ) return;

        $tax_query = \'\';
        $terms = $this->get_terms_to_exclude(); // see function below

        if( $terms ) 
            $tax_query = array(
                   array(
                        \'taxonomy\' => $this->tax,
                        \'field\' => \'slug\',
                        \'terms\' => $terms,
                        \'operator\'=>\'NOT IN\'
                    )
            );

        // if after all that we have a tax query to make, lets do it!
        if ( $tax_query )
            set_query_var(\'tax_query\', $tax_query);

    }

    } //end class

    global $Site_Members_Taxonomy;
    $Site_Members_Taxonomy = new Site_Members_Taxonomy();

}

// finally, outside the class definition, there is a function `members_can_view` to be used as a conditional to hide/show various template tags etc.

问题是，在单贴视图中，next_post_link() 和previous_post_link() 不要使用过滤器，这样访问者就可以导航到他们想要的帖子cannot 阅读我想过滤这些帖子的链接，只显示下一篇他们可以阅读的帖子的链接。

我基本上希望在get\\u nextigation\\u post（）上使用上面的查询过滤器。

在里面WP core trac for link-template.php （以及下面链接的Kaiser帖子）我发现next_post_link(), get_next_post() 和get_adjacent_post() 通过以下筛选器运行相邻的post查询：

• get_{$adjacent}_post_join
• get_{$adjacent}_post_where
• get_{$adjacent}_post_sort

REWRITE JOIN/WHERE FILTER

此功能当前在站点上处于活动状态，不会引发错误，但也不会正确过滤相邻的帖子查询。

Current Question: 在下面的函数filter\\u neighbent中将$excluded\\u terms从slug转换为id时，我是否正确构建了数组？我如何记录排除的条款并了解发生了什么？

    // Filters for get_adjacent_posts() so they don\'t show up in single-post navigation  
    // These filters are added within function __construct{} noted above
    // CHANGE: &$this to $this

    add_filter( \'get_previous_post_where\', array( $this, \'filter_adjacent\' ) );
    add_filter( \'get_next_post_where\', array( $this, \'filter_adjacent\' ) );
    add_filter( \'get_previous_post_join\', array( $this, \'filter_adjacent\' ) );
    add_filter( \'get_next_post_join\', array( $this, \'filter_adjacent\' ) );


    /**
     * These functions added within mu-plugin class:
     *
     * First, modify excluded terms based on membership taxonomy
     * 
     * NOTE: Excluded terms may be an array
     */

    function get_terms_to_exclude() {

        // if a real admin or "level1" we won\'t change tax query at all
        if( current_user_can ( \'manage_options\' ) || current_user_can ( \'view_level1_posts\' ) )
            return false;

        // default/public will exclude all upper level posts
        // in other words, all posts with membership taxonomy
        $terms = array( \'level1\',\'level2\',\'level3\' );

        // if a level3 reader we\'ll exclude level1 and level2 posts
        if( current_user_can ( \'view_level3_posts\' ) )
            $terms = array( \'level1\', \'level2\' );

        // if at level2 level we\'ll exclude level1 level posts
        if( current_user_can ( \'view_level2_posts\' ) )
            $terms = array( \'level1\' );

        return $terms;

    }


    /**
     * Next, use these terms to filter the get_adjacent_post JOIN/WHERE
     */

    function filter_adjacent( $clause ) {

        if ( substr_count( current_filter(), \'_post_join\' ) ) { // filtering join

            if ( empty($clause) ) $clause = \'\';
            global $wpdb;
            $clause .=
                " INNER JOIN {$wpdb->term_relationships} AS trmship ON p.ID = trmship.object_id
                INNER JOIN {$wpdb->term_taxonomy} ttmship
                ON trmship.term_taxonomy_id = ttmship.term_taxonomy_id";
            return $clause;

        } elseif ( substr_count( current_filter(), \'_post_where\' ) ) { // filtering where

            $excluded_term_slugs = get_terms_to_exclude();
            if ( ! $excluded_term_slugs ) return $clause; // nothing to filter if no terms
            $excluded_terms = array(); // we needs term ids, let\'s convert slug in terms ids
            foreach ( $excluded_term_slugs as $slug ) {
                $t = get_term_by( \'slug\',  $slug, \'membership\' );
                if ( ! $t || is_wp_error($t) ) continue;
                $excluded_terms[] = $t;
            }
            // something wrong in get_level_term_to_exclude()?
            if ( empty($excluded_terms) ) return $where; 

            $posts_in_ex_terms_sql = 
                " AND ttmship.taxonomy = \'membership\'
                AND ttmship.term_id NOT IN (" . implode( $excluded_terms, \',\' ) . \')\';
            // return filtered where clause
            return $clause. $posts_in_ex_terms_sql;
        }
    }