从数据库结果生成多维数组的递归函数 [英] Recursive function to generate multidimensional array from database result

问题描述

我希望编写一个函数，该函数接受一组页面/类别(来自平面数据库结果)并基于父 ID 生成一组嵌套页面/类别项.我想递归地执行此操作，以便可以完成任何级别的嵌套.

I'm looking to write a function that takes an array of pages/categories (from a flat database result) and generates an array of nested page/category items based on the parent ids. I would like to do this recursively, so that any level of nesting can be done.

例如:我在一个查询中获取所有页面，这就是数据库表的样子

For example: I'm fetching all the pages in one query, and this is the what the database table looks like

+-------+---------------+---------------------------+
|   id  |   parent_id   |           title           |
+-------+---------------+---------------------------+
|   1   |       0       |   Parent Page             |
|   2   |       1       |   Sub Page                |
|   3   |       2       |   Sub Sub Page            |
|   4   |       0       |   Another Parent Page     |
+-------+---------------+---------------------------+

这是我希望最终在我的视图文件中处理的数组:

And this is the array I would like to end up with to process in my view files:

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
        )
)

我已经查看并尝试了我遇到的几乎所有解决方案(Stack Overflow 上有很多解决方案，但没有运气获得足够通用的东西，既适用于页面又适用于类别.

I've looked and tried nearly every solution I've come across (there's a lot of them here on Stack Overflow, but have had no luck getting something generic enough that will work for both pages and categories.

这是我得到的最接近的，但它不起作用，因为我将孩子分配给一级父母.

Here's the closest I've gotten, but it doesn't work because I'm assigning the children to the first level parent.

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);
}

推荐答案

一些非常简单的通用树构建:

Some very simple, generic tree building:

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:

1. 获取所有元素的数组和当前父元素的 id(最初是 0/nothing/null/whatever).
2. 遍历所有元素.
3. 如果元素的 parent_id 与您在 1. 中获得的当前父 ID 匹配，则该元素是父元素的子元素.把它放在你当前孩子的列表中(这里:$branch).
4. 使用您刚刚在 3. 中标识的元素的 id 递归调用该函数，即找到该元素的所有子元素，并将它们添加为 children 元素.
5. 返回您找到的孩子的名单.

1. Take the array of all elements and the id of the current parent (initially 0/nothing/null/whatever).
2. Loop through all elements.
3. If the parent_id of an element matches the current parent id you got in 1., the element is a child of the parent. Put it in your list of current children (here: $branch).
4. Call the function recursively with the id of the element you have just identified in 3., i.e. find all children of that element, and add them as children element.
5. Return your list of found children.

换句话说，这个函数的一次执行会返回一个元素列表，这些元素是给定父 ID 的子元素.使用 buildTree($myArray, 1) 调用它，它将返回一个元素列表，其中父 id 为 1.最初调用此函数时父 id 为 0，因此没有父 id 的元素为返回，它们是根节点.该函数递归调用自身以查找子项的子项.

In other words, one execution of this function returns a list of elements which are children of the given parent id. Call it with buildTree($myArray, 1), it will return a list of elements which have the parent id 1. Initially this function is called with the parent id being 0, so elements without parent id are returned, which are root nodes. The function calls itself recursively to find children of children.

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