我有一个不同的问题，在此页面上找不到适合我的解决方案。我需要创建一棵树，但不知道根 id。这意味着我必须遍历我的平面数组并在树的顶部构建具有最父项的分支。
如果其他人需要构建没有根父项 ID 的树，我就是这样做的。
<?php
$rows = [
(object) [
'id' => 1001,
'parentid' => 1000,
'name' => 'test1.1'
],
(object) [
'id' => 1000,
'parentid' => 100,
'name' => 'test1'
],
(object) [
'id' => 1002,
'parentid' => 1000,
'name' => 'test1.2'
],
(object) [
'id' => 1004,
'parentid' => 1001,
'name' => 'test1.1.1'
],
(object) [
'id' => 1005,
'parentid' => 1004,
'name' => 'test1.1.1.1'
],
(object) [
'id' => 100,
'parentid' => 10,
'name' => 'test 0'
],
(object) [
'id' => 1006,
'parentid' => 1002,
'name' => 'test1.2.1'
],
(object) [
'id' => 1007,
'parentid' => 1002,
'name' => 'test1.2.2'
],
];
function add_child(stdClass $parent, stdClass $child) {
if ($child->parentid != $parent->id) {
throw new Exception('Attempting to add child to wrong parent');
}
if (empty($parent->children)) {
$parent->children = [];
} else {
// Deal where already in branch.
foreach ($parent->children as $idx => $chd) {
if ($chd->id === $child->id) {
if (empty($chd->children)) {
// Go with $child, since $chd has no children.
$parent->children[$idx] = $child;
return;
} else {
if (empty($child->children)) {
// Already has this child with children.
// Nothing to do.
return;
} else {
// Both childs have children - merge them.
$chd->children += $child->children;
$parent->children[$idx] = $child;
return;
}
}
}
}
}
$parent->children[] = $child;
}
function build_branch(&$branch, &$rows, &$parent = null) {
$hitbottom = false;
while (!$hitbottom) {
$foundsomething = false;
// Pass 1 - find children.
$removals = []; // Indexes of rows to remove after this loop.
foreach ($rows as $idx => $row) {
if ($row->parentid === $branch->id) {
// Found a child.
$foundsomething = true;
// Recurse - find children of this child.
build_branch($row, $rows, $branch);
add_child($branch, $row);
$removals[] = $idx;
}
}
foreach ($removals as $idx) {
unset($rows[$idx]);
}
// Pass 2 - find parents.
if ($parent === null) {
$foundparent = false;
foreach ($rows as $idx => $row) {
if ($row->id === $branch->parentid) {
// Found parent
$foundsomething = true;
$foundparent = true;
add_child($row, $branch);
unset ($rows[$idx]);
// Now the branch needs to become the parent since parent contains branch.
$branch = $row;
// No need to search for other parents of this branch.
break;
}
}
}
$hitbottom = !$foundsomething;
}
}
function build_tree(array $rows) {
$tree = [];
while (!empty($rows)) {
$row = array_shift($rows);
build_branch($row, $rows);
$tree[] = $row;
}
return $tree;
}
$tree = build_tree($rows);
print_r($tree);