Detailed explanation of steps to implement unlimited comment nesting in PHP

This time I will bring you a detailed explanation of the steps to implement unlimited comment nesting in PHP. What are the precautions for implementing unlimited comment nesting in PHP? The following is a practical case, let's take a look.

In the process of designing BB, I have been thinking about whether it is possible to achieve infinite classification structure display and parent-child structure search without recursion, because if the algorithm here is not optimized, the consequences may be fatal! Just imagine, if an article has 300 comments, according to the normal recursive algorithm, the database must be queried at least 301 times, and this is without any nesting. If there are one or two levels of nesting or the number of comments exceeds 1,000 , then the database doesn’t crash directly?

In fact, PHP's powerful array processing capabilities can already help us solve this problem quickly and conveniently. The following figure shows an infinite-level classified

database structure:

IDparentID newsID commts

108 comments with article ID 8
21 8 replies to comments with ID 1
328 Reply to the comment with ID 2

To display the comment with article number 8 in the front desk in a nested manner, in fact, we only need to query the database once, that is, "SELECT * FROM TABLE WHERE newsID=8" , and leave the later recursive work to the powerful

PHP array. The problem that may be involved here is the reorganization of the structural relationship of the array, that is, putting all the comments that stay in the first-level category under their own parentID to form the children item. Paste the code of this piece of code in the BBComment class below. I hope to share my ideas with you, and hope that everyone can come up with better and more efficient algorithms.

Method One

/** 
 * 按ID条件从评论数组中递归查找 
 * 
 */ 
function getCommentsFromAryById($commtAry, $id) 
{ 
 if ( !is_array($commtAry) ) return FALSE; 
 foreach($commtAry as $key=>$value) { 
  if ( $value['id'] == $id ) return $value; 
  if ( isset($value['children']) && is_array($children) ) $this->getCommentsFormAryById($value['children'], $id); 
 } 
} 
/** 
 * 追加 子评论 到 主评论 中，并形成children子项 
 * 
 * @param array $commtAry 原评论数据引用 
 * @param int $parentId 主评论ID 
 * @param array $childrenAry 子评论的值 
 */ 
function addChildenToCommentsAry($commtAry, $parentId, $childrenAry) 
{ 
 if ( !is_array($commtAry) ) return FALSE; 
 foreach($commtAry as $key=>$value) { 
  if ( $value['id'] == $parentId ) { 
   $commtAry[$key]['children'][] = $childrenAry; 
   return TRUE; 
  } 
  if ( isset($value['children']) ) $this->addChildenToCommentsAry($commtAry[$key]['children'], $parentId, $childrenAry); 
 } 
} 
 $result = $this->BBDM->select($table, $column, $condition, 0, 1000); 
 /* 开始进行嵌套评论结构重组 */ 
 array_shift($result); 
 $count = count($result); 
 $i  = 0; 
 while( $i<$count ) { 
  if ( &#39;0&#39; != $result[$i][&#39;parentId&#39;] ) { 
   $this->addChildenToCommentsAry($result, $result[$i][&#39;parentId&#39;], $result[$i]); 
   unset($result[$i]); 
  } 
  $i++; 
 } 
 $result = array_values($result); 
 /* 重组结束 */

Implementation Method Two

The core code is extracted from WordPress

<?php
$comments = array (
  array (
    &#39;id&#39; => &#39;3&#39;,
    &#39;parent&#39; => &#39;0&#39;
  ),
  array (
    &#39;id&#39; => &#39;9&#39;,
    &#39;parent&#39; => &#39;0&#39;
  ),
  array (
    &#39;id&#39; => &#39;1&#39;,
    &#39;parent&#39; => &#39;3&#39;
  ),
  array (
    &#39;id&#39; => &#39;2&#39;,
    &#39;parent&#39; => &#39;3&#39;
  ),
  array (
    &#39;id&#39; => &#39;5&#39;,
    &#39;parent&#39; => &#39;1&#39;
  ),
  array (
    &#39;id&#39; => &#39;7&#39;,
    &#39;parent&#39; => &#39;1&#39;
  )
);
function html5_comment($comment) {
  echo &#39;<li>&#39;;
  echo &#39;id:&#39;, $comment[&#39;id&#39;], &#39; parent:&#39;, $comment[&#39;parent&#39;];
}
function start_el(& $output, $comment) {
  ob_start();
  html5_comment($comment);
  $output .= ob_get_clean();
}
function end_el(& $output) {
  $output .= "</li><!-- #comment-## -->\n";
}
function start_lvl(& $output) {
  $output .= &#39;<ol class="children">&#39; . "\n";
}
function end_lvl(& $output) {
  $output .= "</ol><!-- .children -->\n";
}
function display_element($e, & $children_elements, $max_depth, $depth, & $output) {
  $id = $e[&#39;id&#39;];
  start_el($output, $e); //当前评论的开始代码
  if ($max_depth > $depth +1 && isset ($children_elements[$id])) { //如果没超过最大层，并且存在子元素数组
    foreach ($children_elements[$id] as $child) {
      if (!isset ($newlevel)) { //第一次循环没设置变量$newlevel，所以把$newlevel设为true，并且开始子元素的开始代码;第二次及之后的循环，已经设置了$newlevel,就不会再添加子元素的开始代码。因为同一批循环时兄弟元素，所以只需要一个子元素开始代码，循环内容为并列关系。
        $newlevel = true;
        start_lvl($output);
      }
      display_element_template($child, $children_elements, $max_depth, $depth +1, $output); //$child作为参数，继续去寻找下级元素
    }
    unset ($children_elements[$id]); //用完释放变量，以后就不会重复判断该值了,递归后继续判断剩下的子元素
  }
  if (isset ($newlevel) && $newlevel) { //如果前面找到了子元素，这里就要执行子元素的结束代码
    end_lvl($output);
  }
  end_el($output); //当前评论的结束代码
}
function display_element_template($e, & $children_elements, $max_depth, $depth, & $output) {
  $id = $e[&#39;id&#39;];
  display_element($e, $children_elements, $max_depth, $depth, $output);
  if ($max_depth <= $depth +1 && isset ($children_elements[$id])) { //如果超出最大层级，并且子元素存在的话，以$child为参数继续往下找
    foreach ($children_elements[$id] as $child) {
      display_element_template($child, $children_elements, $max_depth, $depth, $output);
    }
    unset ($children_elements[$id]); //用完释放变量
  }
}
function comments_list($comments) {
  $top_level_elements = array ();
  $children_elements = array ();
  foreach ($comments as $e) {
    if (0 == $e[&#39;parent&#39;]) {
      $top_level_elements[] = $e;
    } else {
      $children_elements[$e[&#39;parent&#39;]][] = $e;
    }
  }
  $output = &#39;&#39;;
  foreach ($top_level_elements as $e) {
    display_element_template($e, $children_elements, 2, 0, $output);
  }
  //var_dump($children_elements);//由于每次用完$children_elements后都会释放变量，所以到最后$children_elements为空数组
  return $output;
}
echo &#39;<ol class="comment-list">&#39;, comments_list($comments), &#39;</ol>&#39;;

I believe you have mastered it after reading the case in this article Method, for more exciting information, please pay attention to other related articles on the php Chinese website!

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