我在这个论坛上搜索了可能的解决方案，但没有找到任何有效的方法。也许我做得不对。

这是我迄今为止尝试过的代码

$parent_categories = \'\' ;
$sub_categories = \'\';
$subcat = \'\';

$args = array(
\'number\'     => $number,
\'orderby\'    => $orderby,
\'order\'      => $order,
\'hide_empty\' => $hide_empty,
\'include\'    => $ids,
\'hierarchical\'=> true, 
\'parent\'  => 0
);

 $product_categories = get_terms( \'product_cat\', $args );


foreach ($product_categories as $cat) {
//var_dump($cat); echo \'<br>\';

如果（$cat->slug==\'文章\'）{

    $args2 = array(
        \'number\'     => $number,
        \'orderby\'    => $orderby,
        \'order\'      => $order,
        \'hide_empty\' => $hide_empty,
        \'include\'    => $ids,
        \'parent\'     => $cat->term_id,
        \'hierarchical\'=> true, 
    );

    $sub_categories = get_terms( \'product_cat\', $args2 );

    foreach ($sub_categories as $subcat) {
        $sub_categories = $sub_categories.$subcat->name.\',\';
    }

    $sub_categories = rtrim($sub_categories);
}
else
    $sub_categories= \'nomatch\';

}

当我这样做的时候echo $sub_categories.

我得到输出no match;

Debug results

我尝试删除if-else条件，以查看哪些条件有效，哪些条件无效。

$parent_categories = \'\' ;
$sub_categories = \'\';
$subcat = \'\';

$args = array(
\'number\'     => $number,
\'orderby\'    => $orderby,
\'order\'      => $order,
\'hide_empty\' => $hide_empty,
\'include\'    => $ids,
\'hierarchical\'=> true, 
\'parent\'  => 0
);

 $product_categories = get_terms( \'product_cat\', $args );


foreach ($product_categories as $cat) {
//var_dump($cat); echo \'<br>\';

    $args2 = array(
        \'number\'     => $number,
        \'orderby\'    => $orderby,
        \'order\'      => $order,
        \'hide_empty\' => $hide_empty,
        \'include\'    => $ids,
        \'parent\'     => $cat->term_id,
        \'hierarchical\'=> true, 
    );

    $sub_categories = get_terms( \'product_cat\', $args2 );

    foreach ($sub_categories as $subcat) {
        $sub_categories = $sub_categories.$subcat->name.\',\';
    }

    $sub_categories = rtrim($sub_categories);

代码确实检索父类别，并且ALL 的子类别ALL 顶级类别。尽管我想要特定父类别的子类别。我试过了parent=>$cat->term_id 和$cat->term_taxonomy_id. 结果仍然是一样的。我尝试对家长的term\\u id进行硬编码，但没有用。

好的，所以我的第一个任务是获取特定类别的子类别！

我的第二个问题是，为什么if条件（用橙色标记）不能很好地工作？

请让我知道我要在这里做什么修改！

$sub_categories = get_terms( \'product_cat\', $args2 );
echo \'<pre>\';print_r( $sub_categories );

foreach ($sub_categories as $subcat) {
        $sub_categories = $sub_categories.$subcat->name.\',\';
}

$text = \'\';
$i = 0;
foreach ($sub_categories as $subcat){
  if( $i > 0 )
    $text .= \', \';
  $text .= $subcat->name;
  $i = 1;
}
echo $text;

<?php
$parent_categories = \'\' ;
$sub_categories = \'\';
$subcat = \'\';

$args = array(
    \'number\'     => $number,
    \'orderby\'    => $orderby,
    \'order\'      => $order,
    \'hide_empty\' => $hide_empty,
    \'include\'    => $ids,
    \'hierarchical\'=> true, 
    \'parent\'  => 0
);

$product_categories = get_terms( \'product_cat\', $args );
foreach( $product_categories as $cat ) {
    if($cat->slug == \'essays\') {

        $args2 = array(
            \'number\'     => $number,
            \'orderby\'    => $orderby,
            \'order\'      => $order,
            \'hide_empty\' => $hide_empty,
            \'include\'    => $ids,
            \'parent\'     => $cat->term_id,
            \'hierarchical\'=> true, 
        );

        $sub_categories = get_terms( \'product_cat\', $args2 );

        $text = \'\';
        $i = 0;
        if( is_array( $sub_categories ) && count( $sub_categories ) > 0 ){
            foreach ($sub_categories as $subcat){
                if( $i > 0 )
                    $text .= \', \';
                $text .= $subcat->name;
                $i = 1;
            }
            $sub_categories; = $text;
        } else {
            $sub_categories= \'nomatch\';
        }
    }
}
?>