我有一个SQL查询返回的对象数组,其中top_id是我的父ID字段:
Array (
[0] => stdClass Object ( [id] => 1 [top_id] => 0 [name] => Cat 1 )
[1] => stdClass Object ( [id] => 2 [top_id] => 0 [name] => Cat 2 )
[2] => stdClass Object ( [id] => 3 [top_id] => 0 [name] => Cat 3 )
[3] => stdClass Object ( [id] => 4 [top_id] => 2 [name] => Subcat 1 )
[4] => stdClass Object ( [id] => 5 [top_id] => 2 [name] => Subcat 2 )
[5] => stdClass Object ( [id] => 6 [top_id] => 3 [name] => Subcat 3 )
[6] => stdClass Object ( [id] => 7 [top_id] => 5 [name] => Subcat 4 )
)
现在我需要使用PHP获得一个嵌套列表:
<ul>
<li>Cat 1</li>
<li>Cat 2
<ul>
<li>Subcat 1</li>
<li>Subcat 2
<ul>
<il>Subcat 3
<ul>
<li>Subcat 4</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li>Cat 3</li>
</ul>
任何想法?由于
首先将对象映射到索引为id
的新散列(数组):
// map the array onto hash
$hash = array();
foreach($array as $object)
{
$hash[$object->id] = array('object' => $object);
}
然后将这个平面散列转换为树状结构,参见另一个代码示例的答案,这里只是相同的:
// build tree from hash
$tree = array();
foreach($hash as $id => &$node)
{
if ($parent = $node['object']->top_id)
$hash[$parent]['children'][] =& $node;
else
$tree[] =& $node;
}
unset($node, $hash);
最后,您可以将这个树状结构输出为HTML。这可以通过堆栈或递归来实现。这是递归的一个变体:
// render tree
function render_tree($tree)
{
echo '<ul>', "'n";
foreach($tree as $node)
{
render_node($node);
}
echo '</ul>';
}
// render tree node
function render_node($node, $level = 0)
{
$inset = str_repeat(' ', $level) . ' ';
echo $inset, '<li>', $node['object']->name;
if (isset($node['children']))
{
echo "'n", $inset, ' <ul>', "'n";
foreach($node['children'] as $node)
{
render_node($node, $level+1);
}
echo $inset, ' </ul>', "'n", $inset;
}
echo '</li>', "'n";
}
// output
render_tree($tree);
输出:<ul>
<li>Cat 1</li>
<li>Cat 2
<ul>
<li>Subcat 1</li>
<li>Subcat 2
<ul>
<li>Subcat 4</li>
</ul>
</li>
</ul>
</li>
<li>Cat 3
<ul>
<li>Subcat 3</li>
</ul>
</li>
</ul>
完整代码示例+ HTML演示。