此代码手动设置订单\'order\' => \'ASC\' WP\\u查询参数中的声明。

$loop = new WP_Query( array(
  \'post_type\' => \'product\',
  \'meta_key\' => \'product_price\',
  \'orderby\' => \'meta_value_num\',
  \'order\' => \'ASC\',
  \'posts_per_page\' => 4,
  \'paged\' => $paged) );

如果要将url参数传递给该参数，可以使用如下内容：

\'order\' => $_GET[\'posts_order\']

以及url模式，如：/?posts_order=ASC

但那将是一个可怕的想法。。。因为有人可以访问url：/?posts_order=DROP TABLE IF EXISTS table1 &；可能会破坏事物。

因此，如果我们要侦听url中的变量，我们需要对其进行清理。

<?php 
if ( ! empty( $_GET[\'posts_order\'] ) ) {
  $posts_order = sanitize_key( $_GET[\'posts_order\'] );  // prevent malicious characters in user-submitted variable
}

或者，更好的是，我们可以使用白名单方法&；仅允许的某些值

$posts_order = \'DESC\';
if ( ! empty( $_GET[\'posts_order\'] ) ) {
  $posts_order_raw = sanitize_key( $_GET[\'posts_order\'] );
  if ( \'ASC\' === $posts_order_raw ) {
    $posts_order = \'ASC\';
  }
}

$loop = new WP_Query( array(
  \'post_type\' => \'product\',
  \'meta_key\' => \'product_price\',
  \'orderby\' => \'meta_value_num\',
  \'order\' => $posts_order,
  \'posts_per_page\' => 4,
  \'paged\' => $paged) ); 

但是等等，还有更多！

我们可以从WP\\u查询中完全省略订单声明

$loop = new WP_Query( array(
  \'post_type\' => \'product\',
  \'meta_key\' => \'product_price\',
  \'orderby\' => \'meta_value_num\',
  // \'order\' => $posts_order, # Remove this line #
  \'posts_per_page\' => 4,
  \'paged\' => $paged) );

&；相反，从pre_get_posts 挂钩：

<?php
function wp_se_331547( $wp_query ) {

  if ( !is_admin() && is_main_query() ) {
    if( \'product\' === get_post_type() ) {
      $posts_order = \'DESC\';
      if ( ! empty( $_GET[\'posts_order\'] ) ) {
        $posts_order_raw = sanitize_key( $_GET[\'posts_order\'] );
        if ( \'ASC\' === $posts_order_raw ) {
          $posts_order = \'ASC\';
        }
      }
      $wp_query->set( \'order\', $posts_order );
    }
  }

}
add_action(\'pre_get_posts\', \'wp_se_331547\');