我正在使用WP\\u Query按用户输入对帖子进行排序。输入包含元值，该值显示在选择类型字段中。

通常，当表单中插入值时，wp\\u查询工作正常。但是，如果用户希望对所有帖子进行排序，而不管meta值是什么，那又如何呢？

我的意思是：

//this is my input form 
<select name"rating">
<option value="">Show all</option> //if user select this, show all post, regardless the rating
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
 </select> 

//here is for WP_Query
$args = array(
\'post_type\'=>array(\'listing\',\'renting\'),
\'posts_per_page\'=> 6,
\'order\' => \'DESC\',
\'meta_query\' => array(
\'relation\' => \'AND\',
 array(
        \'key\' => \'rating\',
        \'value\' => $_GET[\'rating\']//here is what I don\'t understand, what if no value in this field?is it take the value as "0"?
    ),
......
),  

正如您所看到的，在select表单中，有一个选项将显示所有帖子，无论评分如何。我该怎么做呢？

谢谢

if ( (isset($_GET[\'rating\']) && !empty($_GET[\'rating\']) ) {
            // restrict
   $meta[] = array((
    \'key\' => \'rating\',
    \'value\' => $_GET[\'rating\'] );

} 
if ( (isset($_GET[\'tax\']) && !empty($_GET[\'tax\']) ) {
    $meta[] = array((
    \'key\' => \'tax\',
    \'value\' => $_GET[\'tax\'] );

}

$args = array(
         \'post_type\'=>array(\'listing\',\'renting\'),
         \'posts_per_page\'=> 6,
         \'order\' => \'DESC\',
         \'meta_query\' => array( \'relation\' => \'AND\', $meta )

     );