PHP - 如何构建树结构列表? [英] PHP - How to build tree structure list?

问题描述

所以，我的问题是，我想构建这两个表的树:

So, my problem is, that I want to build a tree of these 2 tables:

Parent table:
+-------+---------------+
| pr_id |  parent_name  |
+-------+---------------+
|   1   |       p       |
|   2   |      p_0      | 
|   3   |     p_0_1     | 
|   4   |       q       | 
+-------+---------------+

Child table:
+-------+---------------+---------------------------+
| ch_id |     pr_id     |        child_name         |
+-------+---------------+---------------------------+
|   1   |       1       |            p_0            |
|   2   |       1       |            p_1            |
|   3   |       2       |           p_0_0           |
|   4   |       2       |           p_0_1           |
|   5   |       3       |          p_0_1_0          |
|   6   |       3       |          p_0_1_1          |
|   7   |       4       |            q_0            |
|   8   |       4       |            q_1            |
+-------+---------------+---------------------------+

树应该看起来像:

• p
  • p_0
    • p_0_0
    • p_0_1
      • p_0_1_0
      • p_0_1_1

      有人可以帮我解决递归问题吗??

      Can anybody help me out with a recursive solution??

      推荐答案

      您不需要为此在数据库中创建 2 个表，您可以仅从一个表中进行如下维护

      You do not need to create 2 tables in the database for this you can maintain it like below from one table only

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

      生成的数组就像

      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
              )
      )
      

      你需要使用下面的递归函数来实现它

      You need to use the below recursive function to achieve it

      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. 取所有元素的数组和当前父元素的id(最初为 0/无/空/随便什么).
      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.把它放在你的清单中当前孩子的数量(此处:$branch).
      4. 使用您刚刚在 3. 中标识的元素的 id 递归调用该函数，即查找该元素的所有子元素，并将它们添加为子元素.
      5. 返回您找到的孩子的名单.

      这篇关于PHP - 如何构建树结构列表?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！