仅供参考，我不是一个有经验的程序员，而且我对PHP的编码经验很少，可以肯定地说，我不知道基础知识，只是我在阅读、理解和编辑现有代码的过程中自学的内容。

我有一个网站，它有一个购买的主题，其中包括一个自定义的tax\\u查询，我复制了它的结构，以尝试按元数据中的不同字段过滤查询。我把我的函数放在函数中。我的子主题中的php文件，其中包含到目前为止我所做的所有修改。

这是我的代码：

function ah_meta_queries( $query = false ) {
    if ( ! ( is_post_type_archive( \'listing\' ) || is_tax( \'listing_type\' ) || is_tax( \'listing_location\' ) ) ) return;

    if ( is_admin() || ! is_a( $query, \'WP_Query\' ) || ! $query->is_main_query() ) return;

    if ( is_post_type_archive( \'listing\' ) ) {
        $meta_query_args = array( \'relation\' => \'AND\' );

        // For each type of Meta Data, check if filtering is set, then add it to the query array

        if ( isset( $_GET[\'et-listing-rating\'] ) && \'none\' != $_GET[\'et-listing-rating\'] ) {
        $meta_query_args[] = array(
                \'key\' => \'listing_type\',
                \'value\' =>  intval( $_GET[\'et-listing-rating\'] ),
        ); }

        if ( isset( $_GET[\'Fitness\'] ) )
        $meta_query_args[] = array(
                \'key\' => \'HN_Fitness\',
                \'value\' => \'TRUE\',
        );

        if ( isset( $_GET[\'Furnished\'] ) ) 
        $meta_query_args[] = array(
                \'key\' => \'HN_Furnished\',
                \'value\' => \'TRUE\',
        );

        if ( isset( $_GET[\'Kitchen\'] ) ) 
        $meta_query_args[] = array(
                \'key\' => \'HN_Kitchen\', 
                \'value\' => \'TRUE\',
        );

        if ( isset( $_GET[\'Parking\'] ) ) 
        $meta_query_args[] = array(
                \'key\' => \'HN_Parking\',
                \'value\' => \'TRUE\',
        );

        if ( isset( $_GET[\'Pets Allowed\'] ) ) 
        $meta_query_args[] = array(
                \'key\' => \'HN_Pets\',
                \'value\' => \'TRUE\',
        );

        if ( isset( $_GET[\'Pool\'] ) )
        $meta_query_args[] = array(
                \'key\' => \'HN_Pool\',
                \'value\' => \'TRUE\',
        );          

        // If user input Price-Low but no Price-High, make sure Listing Price Low or Listing Price High is more than Price-Low
        if ( (isset( $_GET[\'price-low\'] ) && \'\' !=$_GET[\'price-low\'] ) && !isset( $_GET[\'price-high\']) )
        $meta_query_args[] = array(
                \'relation\' => \'OR\',
                array(  
                    \'key\' => \'HN_Price_Low\',
                    \'value\' => $_GET[\'price-low\'],
                    \'type\' => \'numeric\',
                    \'compare\' => \'>=\', 
                ),
                array(
                    \'key\' => \'HN_Price_High\',
                    \'value\' => $_GET[\'price-low\'],
                    \'type\' => \'numeric\',
                    \'compare\' => \'>=\',
                ),
        );

        // If user input Price-High but no Price-Low, make sure Listing Price Low or Listing Price High is less than Price-High
        if ( !isset( $_GET[\'price-low\']) && (isset( $_GET[\'price-high\'] ) && \'\' !=$_GET[\'price-high\'] ) )
        $meta_query_args[] = array(
                \'relation\' => \'OR\',
                array(  
                    \'key\' => \'HN_Price_Low\',
                    \'value\' => $_GET[\'price-high\'],
                    \'type\' => \'numeric\',
                    \'compare\' => \'<=\', 
                ),
                array(
                    \'key\' => \'HN_Price_High\',
                    \'value\' => $_GET[\'price-high\'],
                    \'type\' => \'numeric\',
                    \'compare\' => \'<=\',
                ),
        );

        // If user input both Price-Low AND Price-High, make sure Listing Price Low or Listing Price High is BETWEEN Price-Low and Price-High
        if ( (isset( $_GET[\'price-low\'] ) && \'\' !=$_GET[\'price-low\'] ) && (isset( $_GET[\'price-high\'] ) && \'\' !=$_GET[\'price-high\'] ) )
        $meta_query_args[] = array(
                \'relation\' => \'OR\',
                array(  
                    \'key\' => \'HN_Price_Low\',
                    \'value\' => array( $_GET[\'price-low\'], $_GET[\'price-high\'] ),
                    \'type\' => \'numeric\',
                    \'compare\' => \'BETWEEN\', 
                ),
                array(
                    \'key\' => \'HN_Price_High\',
                    \'value\' => array( $_GET[\'price-low\'], $_GET[\'price-high\'] ),
                    \'type\' => \'numeric\',
                    \'compare\' => \'BETWEEN\',
                ),
        );



        // If any of the filters are set in the URL, then run the Meta Query

        if (    ( isset( $_GET[\'et-listing-rating\'] ) && \'none\' != $_GET[\'et-listing-rating\'] ) ||
                isset( $_GET[\'Fitness\'] ) ||
                isset( $_GET[\'Furnished\'] ) ||
                isset( $_GET[\'Kitchen\'] ) ||
                isset( $_GET[\'Parking\'] ) ||
                isset( $_GET[\'Pets Allowed\'] ) ||       
                isset( $_GET[\'Pool\'] ) ||       
                ( isset( $_GET[\'price-low\'] ) && \'\' !=$_GET[\'price-low\'] ) ||
                ( isset( $_GET[\'price-high\']) && \'\' !=$_GET[\'price-high\'] )
            )
            $meta_query = new WP_Meta_Query( $meta_query_args );            

    }
}

我的一些问题是：-为什么这个没有运行？是否必须将该函数设置为在其他任何地方运行-为什么函数是用参数（$query=false）声明的？

欢迎提出任何建议！！

add_filter( \'pre_get_posts\', \'ah_meta_queries\' );