多维数组树缺少节点

Question

尝试使用以下代码在多维数组中创建树

$source = array(
(array('id'=>406,'parent'=>0,'title'=>'level_0_406')),
(array('id'=>270,'parent'=>268,'title'=>'level_0_406_268_270')),
(array('id'=>271,'parent'=>268,'title'=>'level_0_406_268_271')),
(array('id'=>272,'parent'=>268,'title'=>'level_0_406_268_272')),
(array('id'=>273,'parent'=>268,'title'=>'level_0_406_268_273)')),
(array('id'=>269,'parent'=>268,'title'=>'level_0_406_268_269')),
(array('id'=>268,'parent'=>406,'title'=>'level_0_406_268')),
(array('id'=>407,'parent'=>406,'title'=>'level_0_406_407')),
(array('id'=>274,'parent'=>406,'title'=>'level_0_406_274')),
(array('id'=>500,'parent'=>407,'title'=>'level_0_406_407_500')),
);
$result = array();
$links = array(0=>&$result);
foreach ($source as &$element){
    $links[$element['id']] = &$element;     
    $links[$element['parent']]['childs'][$element['id']] = &$element;
}

但结果数组不包含源数组的多个节点，即id=269,270,271,272,273的节点。

Array
(
    [childs] => Array
        (
            [406] => Array
                (
                    [id] => 406
                    [parent] => 0
                    [title] => level_0_406
                    [childs] => Array
                        (
                            [268] => Array
                                (
                                    [id] => 268
                                    [parent] => 406
                                    [title] => level_0_406_268
                                )
                            [407] => Array
                                (
                                    [id] => 407
                                    [parent] => 406
                                    [title] => level_0_406_407
                                    [childs] => Array
                                        (
                                            [500] => Array
                                                (
                                                    [id] => 500
                                                    [parent] => 407
                                                    [title] => level_0_406_407_500
                                                )
                                        )
                                )
                            [274] => Array
                                (
                                    [id] => 274
                                    [parent] => 406
                                    [title] => level_0_406_274
                                )
                        )
                )
        )
)

我尝试了不同的生成树的代码示例，但他们都有相同的问题与源数组，如$source。请帮我理解这种行为。

现在我明白什么是错误的数组。但是，如果我有这样的数据在DB，如何做出正确的选择?

Answer 1

原始$source数组值未正确创建。应该是:-

$source = array(
  (array('id'=>406,'parent'=>0,'title'=>'level_0_406')),
  (array('id'=>268,'parent'=>406,'title'=>'level_0_406_268')),
  (array('id'=>407,'parent'=>406,'title'=>'level_0_406_407')),
  (array('id'=>274,'parent'=>406,'title'=>'level_0_406_274')),
  (array('id'=>270,'parent'=>268,'title'=>'level_0_406_268_270')),
  (array('id'=>271,'parent'=>268,'title'=>'level_0_406_268_271')),
  (array('id'=>272,'parent'=>268,'title'=>'level_0_406_268_272')),
  (array('id'=>273,'parent'=>268,'title'=>'level_0_406_268_273)')),
  (array('id'=>269,'parent'=>268,'title'=>'level_0_406_268_269')),
  (array('id'=>500,'parent'=>407,'title'=>'level_0_406_407_500')),
);

如果您仔细观察，您将看到前面只有父元素ID 407的子元素是可用的，因为元素ID 407在子元素出现之前已经定义了。

实际上，您的编码逻辑是首先定义父元素，然后定义子元素。还有一般做法&标准一直都是一样的。

在我的答案中，我已经正确地改变了元素的出现。这应该可以工作。

希望能有所帮助。