[英]Echo menu tree with recursive function
問題:我想不出對我的具體情況使用遞歸函數的方式。
情況:
Mysql DB
id | root | name |
root
向女巫類別顯示時,這是子類別。
HTML應該如何顯示:
<li><a href="#"><p class="Tier0">Datori</p></a>
<ul style="display: block">
<li><a href="#"><p class="Tier1">Cookies</p></a></li>
<li><a href="#"><p class="Tier1">Events</p></a></li>
<li><a href="#"><p class="Tier1">Forms</p></a></li>
<li><a href="#"><p class="Tier1">Games</p></a></li>
<li><a href="#"><p class="Tier1">Images</p></a>
<ul>
<li><a href="#"><p class="Tier2">CSS</p></a></li>
<li><a href="#"><p class="Tier2">JavaScript</p></a></li>
<li><a href="#"><p class="Tier2">JQuery</p></a></li>
</ul>
</li>
<li><a href="#"><p class="Tier1">Navigations</p></a>
<ul>
<li><a href="#"><p class="Tier2">CSS</p></a></li>
<li><a href="#"><p class="Tier2">JavaScript</p></a></li>
<li><a href="#"><p class="Tier2">JQuery</p></a></li>
</ul>
</li>
<li><a href="#"><p class="Tier1">Tabs</p></a></li>
</ul>
</li>
<li><a href="#"><p class="Tier0">Washing Machines</p></a>
我需要什么樣的PHP函數才能將其全部打印出來?
怎么樣:
function recurse($categories, $parent = null, $level = 0)
{
$ret = '<ul>';
foreach($categories as $index => $category)
{
if($category['root'] == $parent)
{
$ret .= '<li><a href="#"><p class="Tier' . $level . '">' . $category['name'] . '</p></a>';
$ret .= $this->recurse($categories, $category['id'], $level+1);
$ret .= '</li>';
}
}
return $ret . '</ul>';
}
此函數要求您首先在數據庫中查詢可用類別的整個列表,並假設您的根類別的值為null,但是可以根據當前模式的工作方式將該函數更改為接受-1或0。
$categories = { get from database into an multi-dimensional array };
$Tree = $this->recurse($categories);
echo $Tree;
您可以考慮執行以下操作,以防止在父級不存在任何子級時出現任何空的UL:
function recurse($categories, $parent = null, $level = 0)
{
$ret = '<ul>';
foreach($categories as $index => $category)
{
if($category['root'] == $parent)
{
$ret .= '<li><a href="#"><p class="Tier' . $level . '">' . $category['name'] . '</p></a>';
$sub = $this->recurse($categories, $category['id'], $level+1);
if($sub != '<ul></ul>')
$ret .= $sub;
$ret .= '</li>';
}
}
return $ret . '</ul>';
}
但是,最好的解決方案是選擇數據以包括一列,該列包含每個類別有多少個子類別。
select Category.*, (select count(distinct c1.id) from Category as c1 where c1.root = Category.id) as ChildCount from Category
您的功能將是:
function recurse($categories, $parent = null, $level = 0)
{
$ret = '<ul>';
foreach($categories as $index => $category)
{
if($category['root'] == $parent)
{
$ret .= '<li><a href="#"><p class="Tier' . $level . '">' . $category['name'] . '</p></a>';
if($category['ChildCount'] > 0)
$ret .= $this->recurse($categories, $category['id'], $level+1);
$ret .= '</li>';
}
}
return $ret . '</ul>';
}
希望有幫助嗎?
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