Php 从数据库结果生成多维数组的递归函数
我想写一个函数，它接受一个页面/类别数组（来自一个平面数据库结果），并根据父ID生成一个嵌套页面/类别项数组。我希望递归地这样做，以便可以进行任何级别的嵌套 例如：我在一个查询中获取所有页面，这就是数据库表的外观Php 从数据库结果生成多维数组的递归函数,php,arrays,function,recursion,Php,Arrays,Function,Recursion,我想写一个函数，它接受一个页面/类别数组（来自一个平面数据库结果），并根据父ID生成一个嵌套页面/类别项数组。我希望递归地这样做，以便可以进行任何级别的嵌套 例如：我在一个查询中获取所有页面，这就是数据库表的外观 +-------+---------------+---------------------------+ | id | parent_id | title | +-------+---------------+----------
+-------+---------------+---------------------------+
| id | parent_id | title |
+-------+---------------+---------------------------+
| 1 | 0 | Parent Page |
| 2 | 1 | Sub Page |
| 3 | 2 | Sub Sub Page |
| 4 | 0 | Another Parent Page |
+-------+---------------+---------------------------+
Array
(
[0] => Array
(
[id] => 1
[parent_id] => 0
[title] => Parent Page
[children] => Array
(
[0] => Array
(
[id] => 2
[parent_id] => 1
[title] => Sub Page
[children] => Array
(
[0] => Array
(
[id] => 3
[parent_id] => 1
[title] => Sub Sub Page
)
)
)
)
)
[1] => Array
(
[id] => 4
[parent_id] => 0
[title] => Another Parent Page
)
)
function page_walk($array, $parent_id = FALSE)
{
$organized_pages = array();
$children = array();
foreach($array as $index => $page)
{
if ( $page['parent_id'] == 0) // No, just spit it out and you're done
{
$organized_pages[$index] = $page;
}
else // If it does,
{
$organized_pages[$parent_id]['children'][$page['id']] = $this->page_walk($page, $parent_id);
}
}
return $organized_pages;
}
function page_list($array)
{
$fakepages = array();
$fakepages[0] = array('id' => 1, 'parent_id' => 0, 'title' => 'Parent Page');
$fakepages[1] = array('id' => 2, 'parent_id' => 1, 'title' => 'Sub Page');
$fakepages[2] = array('id' => 3, 'parent_id' => 2, 'title' => 'Sub Sub Page');
$fakepages[3] = array('id' => 4, 'parent_id' => 3, 'title' => 'Another Parent Page');
$pages = $this->page_walk($fakepages, 0);
print_r($pages);
}
一些非常简单、通用的树构建：
function buildTree(array $elements, $parentId = 0) {
$branch = array();
foreach ($elements as $element) {
if ($element['parent_id'] == $parentId) {
$children = buildTree($elements, $element['id']);
if ($children) {
$element['children'] = $children;
}
$branch[] = $element;
}
}
return $branch;
}
$tree = buildTree($rows);
0null父级\u id$branch子元素换句话说，此函数的一次执行返回一个元素列表，这些元素是给定父id的子元素。使用
buildTree（$myArray，1）调用它$categoryArr = Array();
while($categoryRow = mysql_fetch_array($category_query_result)){
$categoryArr[] = array('parentid'=>$categoryRow['parent_id'],
'id'=>$categoryRow['id']);
}
我知道这个问题很老了，但我遇到了一个非常类似的问题——除了大量的数据。经过一些努力，我成功地在resultset的一个过程中构建了一棵树——使用引用。这段代码并不漂亮，但它工作起来很快。它是非递归的——也就是说，resultset上只有一个过程然后在末尾添加一个
array\u filter$dbh = new PDO(CONNECT_STRING, USERNAME, PASSWORD);
$dbs = $dbh->query("SELECT n_id, n_parent_id from test_table order by n_parent_id, n_id");
$elems = array();
while(($row = $dbs->fetch(PDO::FETCH_ASSOC)) !== FALSE) {
$row['children'] = array();
$vn = "row" . $row['n_id'];
${$vn} = $row;
if(!is_null($row['n_parent_id'])) {
$vp = "parent" . $row['n_parent_id'];
if(isset($data[$row['n_parent_id']])) {
${$vp} = $data[$row['n_parent_id']];
}
else {
${$vp} = array('n_id' => $row['n_parent_id'], 'n_parent_id' => null, 'children' => array());
$data[$row['n_parent_id']] = &${$vp};
}
${$vp}['children'][] = &${$vn};
$data[$row['n_parent_id']] = ${$vp};
}
$data[$row['n_id']] = &${$vn};
}
$dbs->closeCursor();
$result = array_filter($data, function($elem) { return is_null($elem['n_parent_id']); });
print_r($result);
mysql> select * from test_table;
+------+-------------+
| n_id | n_parent_id |
+------+-------------+
| 1 | NULL |
| 2 | NULL |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 2 |
| 7 | 5 |
| 8 | 5 |
+------+-------------+
print\rArray
(
[1] => Array
(
[n_id] => 1
[n_parent_id] =>
[children] => Array
(
[3] => Array
(
[n_id] => 3
[n_parent_id] => 1
[children] => Array
(
)
)
[4] => Array
(
[n_id] => 4
[n_parent_id] => 1
[children] => Array
(
)
)
)
)
[2] => Array
(
[n_id] => 2
[n_parent_id] =>
[children] => Array
(
[5] => Array
(
[n_id] => 5
[n_parent_id] => 2
[children] => Array
(
[7] => Array
(
[n_id] => 7
[n_parent_id] => 5
[children] => Array
(
)
)
[8] => Array
(
[n_id] => 8
[n_parent_id] => 5
[children] => Array
(
)
)
)
)
[6] => Array
(
[n_id] => 6
[n_parent_id] => 2
[children] => Array
(
)
)
)
)
)
这正是我想要的。从这里的其他答案中汲取灵感，我提出了自己的版本，通过使用自定义函数列表在每个级别获得分组键，递归地（任意深度）对assoc数组的数组进行分组 这里是的简化版本（具有更多用于调整旋钮的参数）。请注意，它使用一个简单的作为子例程，用于在各个级别执行分组
/**
* - Groups a (non-associative) array items recursively, essentially converting it into a nested
* tree or JSON like structure. Inspiration taken from: https://stackoverflow.com/a/8587437/3679900
* OR
* - Converts an (non-associative) array of items into a multi-dimensional array by using series
* of callables $key_retrievers and recursion
*
* - This function is an extension to above 'groupByFn', which also groups array but only till 1 (depth) level
* (whereas this one does it till any number of depth levels by using recursion)
* - Check unit-tests to understand further
* @param array $data Array[mixed] (non-associative) array of items that has to be grouped / converted to
* multi-dimensional array
* @param array $key_retrievers Array[Callable[[mixed], int|string]]
* - A list of functions applied to item one-by-one, to determine which
* (key) bucket an item goes into at different levels
* OR
* - A list of callables each of which takes an item or input array as input and returns an int
* or string which is to be used as a (grouping) key for generating multi-dimensional array.
* @return array A nested assoc-array / multi-dimensional array generated by 'grouping' items of
* input $data array at different levels by application of $key_retrievers on them (one-by-one)
*/
public static function groupByFnRecursive(
array $data,
array $key_retrievers
): array {
// in following expression we are checking for array-length = 0 (and not nullability)
// why empty is better than count($arr) == 0 https://stackoverflow.com/a/2216159/3679900
if (empty($data)) {
// edge-case: if the input $data array is empty, return it unmodified (no need to check for other args)
return $data;
// in following expression we are checking for array-length = 0 (and not nullability)
// why empty is better than count($arr) == 0 https://stackoverflow.com/a/2216159/3679900
} elseif (empty($key_retrievers)) {
// base-case of recursion: when all 'grouping' / 'nesting' into multi-dimensional array has been done,
return $data;
} else {
// group the array by 1st key_retriever
$grouped_data = self::groupByFn($data, $key_retrievers[0]);
// remove 1st key_retriever from list
array_shift($key_retrievers);
// and then recurse into further levels
// note that here we are able to use array_map (and need not use array_walk) because array_map can preserve
// keys as told here:
// https://www.php.net/manual/en/function.array-map.php#refsect1-function.array-map-returnvalues
return array_map(
static function (array $item) use ($key_retrievers): array {
return self::groupByFnRecursive($item, $key_retrievers);
},
$grouped_data
);
}
}
请检查Biger with的要点，你不能只使用一个包含所有父ID的数组和另一个页面数组吗？很高兴这有帮助。注意：这有点低效，因为它总是向下传递整个
$elementsarray$elementsarray$elements$rows$children=buildTree（…）