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 |
+-------+---------------+---------------------------+
这是我希望在视图文件中处理的数组:
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
)
)
我已经看过并尝试了几乎所有我遇到的解决方案(这里有很多关于堆栈溢出的解决方案,但是没有运气得到足够通用的、既适用于页面又适用于类别的解决方案)
这是我得到的最接近的结果,但它不起作用,因为我将孩子分配给第一级家长
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);
算法非常简单:
0
/nothing/null
/which)父级\u id
与您在1中获得的当前父级id匹配,则该元素是父级的子级。请将其放入当前子级列表中(此处:$branch
)子元素
元素换句话说,此函数的一次执行返回一个元素列表,这些元素是给定父id的子元素。使用
buildTree($myArray,1)调用它
,它将返回父id为1的元素列表。最初调用此函数时,父id为0,因此返回没有父id的元素,这些元素是根节点。该函数递归调用自身以查找子元素的子元素。可以使用php将mysql结果放入数组中,然后使用它
$categoryArr = Array();
while($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);
对该数据执行时:
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 |
+------+-------------+
最后一次print\r
生成此输出:
Array
(
[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
$elements
数组。对于不重要的小数组,但对于大数据集,你需要删除already在传递之前匹配了其中的元素。但这会变得有些混乱,所以为了便于您理解,我将其保留为简单的。:@deceze我也希望看到混乱的版本。提前谢谢!请解释一下buildTree()中的第一个参数“array”是什么?这是否应该是您给初始页面数组等的变量,例如“$tree=array”?还有人能解释最后一行“$tree=buildTree($rows)”吗,因为“$rows”在任何地方都没有定义?最后,我正在努力使用HTML标记生成嵌套列表。@userarray
是$elements
的类型提示,第一个参数只是array$elements
$rows
是一个数据库结果数组,类似于问题中的结果。@用户我已经添加了一个解释。忽略$children=buildTree(…)
部分,函数应该非常明显和简单。虽然解决方案很聪明,但这段代码有bug,但它在不同的情况下给了我不同的结果situations@Mohammadhzp去年我一直在生产中使用此解决方案,没有任何问题。如果您的数据不同,您将得到不同的结果:)@AleksG:I在评论之前更新您的答案,我必须将isset($elem['children'])添加到数组过滤器回调中,类似于返回isset($elem['children'])和is_null($elem['n\u parent\u id');让它工作right@Mohammadhzp通过您的更改,如果顶级元素没有任何子元素,代码将不起作用-它将从数组中完全删除。@AleksG,使用最新版本的php,如果我删除isset($elem['children']),并且顶级元素包含子元素,则结果对我来说不是这样,我会得到顶级元素的两个不同数组(一个有子元素,一个没有子元素)“我2分钟前刚刚再次测试,没有isset(),我得到了不同(错误)的结果”