递归PHP函数，用于显示邻接表 [英] Recursive PHP function for adjacency-list display

问题描述

我有一个这样的数据库:

I have a DB like so:

id  text           parent
1   Parent 1        0   
2   Child of 1      1   
3   Sibling         1   
4   Another Parent  0 
5   A first child   4

因此，我尝试捕获列出父母的树形结构.我知道其他选择(我认为是嵌套套?)，但现在我要坚持使用.我现在正在尝试将数据从数据库中取出，并放入PHP中的嵌套数组结构中.我有这样的功能:

So I'm trying to capture a tree structure my listing the parents. I'm aware of the other option (nested sets I think?) but I'm going to stick with this for now. I'm now trying to get the data out of the DB and into a nested array structure in PHP. I have a function like this:

class Data_Manager
{   
    public $connection = '';
    public $collection = array();

    function __construct() {
        $this->connection = mysql_connect('localhost', 'root', 'root');
        $thisTable = mysql_select_db('data');
            // error handling truncated
    }


    function get_all() {
        $arr = &$this->collection;

        $this->recurseTree('', 0, $arr);
        var_dump($arr);
    }

    function recurseTree($parent, $level, $arrayNode) {
        $result = mysql_query('SELECT * FROM tasks WHERE parent="' . $parent . '";');

        while ($row = mysql_fetch_array($result)) {
            $row['children'] = array(); //where I'd like to put the kids    
            $arrayNode[$row['id']]= $row;
            $this->recurseTree($row['id'], $level+1, $arrayNode[$row['id']]);
        }
    }
}

所以我想得出的是某种嵌套的关联数组树，但是我不知道该怎么做.我传递的数组似乎什么都没写，在递归中我有点迷失了自己.任何人都可以帮助我克服最后的困难，这会导致类似以下情况:

So what I'd like to come out with is some kind of nested tree of associative arrays, but I can't figure out quite how to do that. Nothing seems to be writing to the array I pass in, and I'm sort of losing track of myself in the recursion. Can anyone help get me over this last hump that will result in something like:

[
Parent1 => [
               children => ['Child of 1', 'Sibling']
           ],
AnotherParent => [
                     children => ['First Child']
                 ]
]

我不太关心输出的具体形式.它将变成JSON，并且我还没有编写客户端处理程序，因此不必担心确切的结构.

And I'm less concerned with the specific form of the output. It will be turned into JSON and I haven't dealt with writing up the client-side handler yet, so no worries on exact structure.

谢谢！

推荐答案

尝试一下.

$sql = "SELECT * FROM tasks";
$r = mysql_query($sql, $conn);
$arr = array();
while ($row = mysql_fetch_assoc($r))
   $arr[] = $row

function build($arrayIn, $parent)
{
    $makeFilter = function($p) {return function($x) use ($p) {return $x['parent'] == $p;};};
    $f = $makeFilter($parent);
    $these = array_filter($arrayIn, $f);
    $remaining = array_diff_assoc($arrayIn, $these);
    $ans = array();

    foreach($these as $cur)
    {
       $ans[$cur['text']] = build($remaining, $cur['id']);
    }
    return $ans ? $ans : null;
}

$tree = build($arr, 0)
echo_r($arr);
echo "becomes<br />";
echo_r($tree);

这是我的输出:

Array
(
[0] => Array
    (
        [text] => a
        [id] => 1
        [parent] => 0
    )

[1] => Array
    (
        [text] => b
        [id] => 2
        [parent] => 0
    )

[2] => Array
    (
        [text] => c
        [id] => 3
        [parent] => 1
    )

[3] => Array
    (
        [text] => d
        [id] => 4
        [parent] => 2
    )

[4] => Array
    (
        [text] => e
        [id] => 5
        [parent] => 2
    )

[5] => Array
    (
        [text] => f
        [id] => 6
        [parent] => 3
    )

)

becomes

Array
(
[a] => Array
    (
        [c] => Array
            (
                [f] => 
            )

    )

[b] => Array
    (
        [d] => 
        [e] => 
    )

)

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