我有一个具有树数据结构的 MySQL 表。这些字段是 _id
, name
和 parentId
.当记录没有父项时,parentId
默认为 0。这样我就可以构建一个数组,然后递归地打印每条记录。
构建的数组如下所示:
Array
(
[1] => Array
(
[parentId] => 0
[name] => Countries
[_id] => 1
[children] => Array
(
[2] => Array
(
[parentId] => 1
[name] => America
[_id] => 2
[children] => Array
(
[3] => Array
(
[parentId] => 2
[name] => Canada
[_id] => 3
[children] => Array
(
[4] => Array
(
[parentId] => 3
[name] => Ottawa
[_id] => 4
)
)
)
)
)
[5] => Array
(
[parentId] => 1
[name] => Asia
[_id] => 5
)
[6] => Array
(
[parentId] => 1
[name] => Europe
[_id] => 6
[children] => Array
(
[7] => Array
(
[parentId] => 6
[name] => Italy
[_id] => 7
)
[11] => Array
(
[parentId] => 6
[name] => Germany
[_id] => 11
)
[12] => Array
(
[parentId] => 6
[name] => France
[_id] => 12
)
)
)
[8] => Array
(
[parentId] => 1
[name] => Oceania
[_id] => 8
)
)
)
)
打印无序列表 <ul>
递归非常简单。这是我使用的功能:
function toUL ($arr) {
$html = '<ul>' . PHP_EOL;
foreach ( $arr as $v ) {
$html.= '<li>' . $v['name'] . '</li>' . PHP_EOL;
if ( array_key_exists('children', $v) ) {
$html.= toUL($v['children']);
}
}
$html.= '</ul>' . PHP_EOL;
return $html;
}
但我一直在打印 <select>
以树状结构的方式:
Countries
-- America
---- Canada
------ Ottawa
-- Asia
-- Europe
---- Italy
---- Germany
---- France
-- Oceania
我想打印 --
与元素的深度一样多,但我不知道如何计算深度。
我的问题是:是否可以构建一个 <select>
不知深浅?
提前谢谢你。
最佳答案
传递一个参数来计算迭代次数,如$pass
function toUL ($arr, $pass = 0) {
$html = '<ul>' . PHP_EOL;
foreach ( $arr as $v ) {
$html.= '<li>';
$html .= str_repeat("--", $pass); // use the $pass value to create the --
$html .= $v['name'] . '</li>' . PHP_EOL;
if ( array_key_exists('children', $v) ) {
$html.= toUL($v['children'], $pass+1);
}
}
$html.= '</ul>' . PHP_EOL;
return $html;
}
关于php - 如何递归构建树深度未知的 <select>,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10011194/