这段代码运行良好，列出了所有父、子和孙类别。代码显示了在父级上的引导切换，运行良好。
All I need the grandchildren into another level ul li and the toggle should be on children that contain grandchildren
<ul>
<?php
$get_parent_cats = array(
\'parent\' => \'0\' //get top level categories only
);
$all_categories = get_categories( $get_parent_cats );//get parent categories
foreach( $all_categories as $single_category ){
//for each category, get the ID
$catID = $single_category->cat_ID;
echo \'<li><a data-toggle="collapse" href="#\' . $single_category->name . \'" role="button" aria-expanded="false" aria-controls="\' . $single_category->name . \'">\' . $single_category->name . \'<i class="fas fa-angle-down float-right mt-2"></i></a>\'; //category name & link
$get_children_cats = array(
\'child_of\' => $catID //get children of this parent using the catID variable from earlier
);
$child_cats = get_categories( $get_children_cats );//get children of parent category
echo \'<ul class="collapse show" id="\' . $single_category->name . \'">\';
foreach( $child_cats as $child_cat ){
//for each child category, get the ID
$childID = $child_cat->cat_ID;
//for each child category, give us the link and name
echo \'<li><a href=" \' . get_category_link( $childID ) . \' ">\' . $child_cat->name . \'<span class="float-right">(\'.$child_cat->count.\')</span></a>\';
}
echo \'</ul></li>\';
} //end of categories logic ?>
</ul>
Result of above code
<ul>
<li>
<a data-toggle="collapse" href="#DISPENSERS" role="button" aria-expanded="false" aria-controls="DISPENSERS">Parent1<i class="fas fa-angle-down float-right mt-2"></i></a>
<ul class="collapse show" id="DISPENSERS">
<li>Child</li>
<li>Child</li>
<li>GrandChild</li>
</ul>
</li>
<li>
<a data-toggle="collapse" href="#VULLING" role="button" aria-expanded="false" aria-controls="VULLING">Parent2<i class="fas fa-angle-down float-right mt-2"></i></a>
<ul class="collapse show" id="VULLING">
<li>Child</li>
<li>GrandChild</li>
<li>Child</li>
</ul>
</li>
Requirements
<ul>
<li>Parent1
<ul>
<li>Child</li>
<li> <a data-toggle="collapse" href="#DISPENSERS" role="button" aria-expanded="false" aria-controls="DISPENSERS">Child<i class="fas fa-angle-down float-right mt-2"></i></a>
<ul class="collapse show" id="DISPENSERS">
<li>
<li>GrandChild</li>
<li>GrandChild</li>
</li>
<ul>
<li>Child</li>
</ul>
</li>
</ul>
SO网友:Ivan Shatsky
你不能用简单的for/foreach 循环。这是一个很好的例子，递归可以帮助：
function get_categories_list( $parent, $use_toggle = true ) {
$result = "";
$categories = get_categories( array ( \'parent\' => $parent ) );
if ($categories) {
foreach ($categories as $category) {
$name = $category->name;
// HERE THE RECURSION IS USED TO GET SUBCATEGORIES TREE
$children = get_categories_list( $category->cat_ID );
if ($children) {
// category has children, use expandable style
if ( $use_toggle ) {
$result .= "<li><a data-toggle=\\"collapse\\" href=\\"#${name}\\" role=\\"button\\" aria-expanded=\\"false\\" aria-controls=\\"${name}\\">${name}<i class=\\"fas fa-angle-down float-right mt-2\\"></i></a><ul class=\\"collapse show\\" id=\\"${name}\\">" . $children . "</ul></li>";
} else {
// root categories level, simplified style without toggle
$result .= "<li>${name}<ul>" . $children . "</ul></li>";
}
} else {
// category hasn\'t any children, use endpoint style
$result .= \'<li><a href="\' . get_category_link( $category->cat_ID ) . "\\">${name}<span class=\\"float-right\\">(" . $category->count . \')</span></a></li>\';
}
}
}
return $result;
}
// list categories from root level ( parent = 0 ), no toggle at root level ( $use_toggle = false )
echo \'<ul>\', get_categories_list( 0, false ), \'</ul>\';
