WordPress Dashboard后台非插件纯代码实现自定义字段过滤

前面我们介绍了 WordPress 主题/插件开发自定义文章分类筛选功能图文教程

下面我们记录一下如何在后台实现过滤自定义字段，将以下代码放入 functions.php 文件中代码段如下：

add_filter( 'parse_query', 'jadmin_posts_filter' ); add_action( 'restrict_manage_posts', 'jadmin_posts_filter_restrict_manage_posts' );   function jadmin_posts_filter( $query ) {     global $pagenow;     if ( is_admin() && $pagenow=='edit.php' && isset($_GET['ADMIN_FILTER_FIELD_NAME']) && '' != $_GET['ADMIN_FILTER_FIELD_NAME']) {         $query->query_vars['meta_key'] = sanitize_text_field($_GET['ADMIN_FILTER_FIELD_NAME']);     if (isset($_GET['ADMIN_FILTER_FIELD_VALUE']) && '' != $_GET['ADMIN_FILTER_FIELD_VALUE'])         $query->query_vars['meta_value'] = sanitize_text_field($_GET['ADMIN_FILTER_FIELD_VALUE']);     } }   function jadmin_posts_filter_restrict_manage_posts() {     global $wpdb;     $sql = 'SELECT DISTINCT meta_key FROM '.$wpdb->postmeta.' ORDER BY 1';     $fields = $wpdb->get_results($sql, ARRAY_N); ?> <select name="ADMIN_FILTER_FIELD_NAME"> <option value=""><?php _e('Filter By Custom Fields', 'jiloc'); ?></option> <?php     $current = isset($_GET['ADMIN_FILTER_FIELD_NAME'])? $_GET['ADMIN_FILTER_FIELD_NAME']:'';     $current_v = isset($_GET['ADMIN_FILTER_FIELD_VALUE'])? $_GET['ADMIN_FILTER_FIELD_VALUE']:'';     foreach ($fields as $field) {         if (substr($field[0],0,1) != "_"){         printf             (                 '<option value="%s"%s>%s</option>',                 $field[0],                 $field[0] == $current? ' selected="selected"':'',                 $field[0]             );         }     } ?> </select> <?php _e('Value:', 'jiloc'); ?><input type="TEXT" name="ADMIN_FILTER_FIELD_VALUE" value="<?php echo $current_v; ?>" /> <?php }