具有递归功能的回显菜单树 [英] Echo menu tree with recursive function
问题描述
问题:我想不出针对我的具体情况制作递归函数的方法.
Problem: I can't think of way make a recursion function to my specific situation.
情况:
Mysql DB
<代码>id |根|姓名|root
向女巫类别显示的地方,这是子类别.
Mysql DB
id | root | name |
Where root
shows to witch category this is subcategory.
HTML 应该是什么样子:
How should HTML look:
<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>
我需要什么样的 PHP 函数才能将其全部打印出来?
What kind of PHP function I would need to print it all out?
推荐答案
怎么样:
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>';
}
此函数要求您首先查询数据库以获取可用类别的整个列表,并假设您的根类别的值为 null,但该函数可以更改为接受 -1 或 0,具体取决于您当前模式的工作方式.
This function requires that you first query your database for the entire list of available categories and assumes that your root categories have a value of null, but the function can be changed to accept -1 or 0 depending on how your current schema works.
$categories = { get from database into an multi-dimensional array };
$Tree = $this->recurse($categories);
echo $Tree;
当父级不存在子级时,您可以考虑执行以下操作以防止出现任何空的 UL:
You may consider doing the following to prevent any empty UL's appearing when no children exist for the parent:
function recurse($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 $ret . '</ul>';
}
但是,最好的解决方案是选择您的数据以包含一列,其中包含每个类别有多少个子类别.
However, the best solution, would be to select your data to include a column containing how many child categories each category has.
select Category.*, (select count(distinct c1.id) from Category as c1 where c1.root = Category.id) as ChildCount from Category
您的函数将在其中:
function recurse($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>';
}
希望有帮助吗?
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