PHP递归以及如何在递归调用中获取数组变量来维护值

我有一个有顶级评论的评论系统，每个评论都可以有无限级别的回复评论。我试图将所有注释id按降序排列到一个数组中

当我只回显结果时，PHP/SQL代码运行良好。但是，我想以数组中正确顺序的注释列表作为结束。当数组变量通过递归例程传递时，它似乎失败了。我理解这是PHP递归中的变量范围问题

那么，为了得到我想要的东西，需要做些什么呢

我的代码：

//get all comments and descendants for post id
function get_comment_list($db,$post_id) {  
        $comment_array = array();
        $sql = "SELECT comment_id FROM comments WHERE parent = 0 AND _post_id=".$post_id." "."ORDER BY dateTime DESC";
        $result = $db->query($sql); 
        $q = $result->fetchAll(PDO::FETCH_COLUMN, 0);//one level array with '0' parameter   
        foreach($q as $parent){
            echo $parent;echo '<br>';//first level parent comment
            $comment_array[] = $parent;//store comment_id's
            get_descendants($db,$parent,$comment_array);    
        }    
    return $comment_array;
}
//get all descendants of parent level comments
function get_descendants($db,$parent,$comment_array){
    $sql = "SELECT comment_id FROM comments WHERE parent = $parent ORDER BY dateTime DESC";
    $result = $db->query($sql);
    $q = $result->fetchAll(PDO::FETCH_COLUMN, 0);//one level array with '0' parameter   
    foreach($q as $item){
        echo '&nbsp;&nbsp;'.$item;echo '<br>';
        $comment_array[]=$item;//store comment_id's
        get_descendants($db,$item,$comment_array);
    }
}
$post_id = 199;
$comment_list = array();
$comment_list = get_comment_list($db,$post_id);
print_r($comment_list);

当我打印数组时，我只得到顶级id。在递归调用期间未添加子体

295
294
244
241
240
237
236
230

或者，您是否可以建议一个按降序进行的递归MYSQL查询

基本数据结构是：

comment_id    comment    parent   post_id

父项将引用注释id作为其父项。parent=0是顶级父级。

请尝试此操作>

    //get all comments and descendants for post id
    function get_comment_list($db,$post_id) {  
            $comment_array = array();
            $sql = "SELECT comment_id FROM comments WHERE parent = 0 AND _post_id=".$post_id." "."ORDER BY dateTime DESC";
            $result = $db->query($sql); 
            $q = $result->fetchAll(PDO::FETCH_COLUMN, 0);//one level array with '0' parameter   
            foreach($q as $parent){
                $comment_array[$parent] = get_descendants($db,$parent);
                //Use Parent ID as a key then push all childs comment under this parent ID
            }    

            print_R($comment_array);die;
        return $comment_array;
    }
    //get all descendants of parent level comments
    function get_descendants($db,$parent,$childComment_array = array()){
       if(empty($childComment_array)){
          $repliedComments = array();
       }else{
           $repliedComments = $childComment_array;
       }

        $sql = "SELECT comment_id FROM comments WHERE parent = $parent ORDER BY dateTime DESC";
        $result = $db->query($sql);
        $q = $result->fetchAll(PDO::FETCH_COLUMN, 0);//one level array with '0' parameter   
        foreach($q as $item){
            $repliedComments[]=$item;
            get_descendants($db,$item,$repliedComments);
        }

return $repliedComments;
    }

---

我发现了一种使用会话数组变量的解决方法。它通过递归函数持续存在。调整代码：

$_SESSION['list']=array();
//get all comments and descendants for post id.  First get parents at = 0, then recurse through children/descendants
function get_comment_list($db,$post_id) {  
        $comment_array = array();
        $sql = "SELECT comment_id FROM comments WHERE parent = 0 AND _post_id=".$post_id." "."ORDER BY dateTime DESC";
        $result = $db->query($sql); 
        $q = $result->fetchAll(PDO::FETCH_COLUMN, 0);//one level array with '0' parameter   
        foreach($q as $parent){
            //echo $parent;echo '<br>';//first level parent comment
            $_SESSION['list'][] = $parent;//store comment_id's
            get_descendants($db,$parent);    
        }    
    return $_SESSION['list'];
}
//get all descendants of parent level comments
function get_descendants($db,$parent){
    $sql = "SELECT comment_id FROM comments WHERE parent = $parent ORDER BY dateTime DESC";
    $result = $db->query($sql);
    $q = $result->fetchAll(PDO::FETCH_COLUMN, 0);//one level array with '0' parameter   
    foreach($q as $item){
        //echo '&nbsp;&nbsp;'.$item;echo '<br>';
        $_SESSION['list'][]=$item;//store comment_id's
        get_descendants($db,$item);
    }
}
$post_id = 199;
$comment_list = get_comment_list($db,$post_id);
print_r($comment_list);
unset($_SESSION['list']);

$\u会话['list']=array（）；
//获取帖子id的所有注释和子体。首先获取=0处的父项，然后通过子项/子体递归
函数get_comment_list（$db，$post_id）{
$comment_array=array（）；
$sql=“从父项为0的注释中选择注释\u id”，“按日期描述排序”；
$result=$db->query（$sql）；
$q=$result->fetchAll（PDO:：FETCH_列，0）；//带有“0”参数的一级数组
foreach（$q作为$parent）{
//echo$parent；echo“
”；//第一级父注释
$\u会话['list'][]=$parent；//存储注释id
获取子代（$db，$parent）；
}    
返回$_会话['list']；
}
//获取父级注释的所有子体
函数get_子体（$db，$parent）{
$sql=“从注释中选择注释\u id，其中父项=$parent ORDER BY dateTime DESC”；
$result=$db->query（$sql）；
$q=$result->fetchAll（PDO:：FETCH_列，0）；//带有“0”参数的一级数组
foreach（$q作为$item）{
//回显“”。$item；回显“
”；
$\会话['list'][]=$item；//存储注释id
获取子体（$db$item）；
}
}
$post_id=199；
$comment\u list=get\u comment\u list（$db，$post\u id）；
打印（评论列表）；
取消设置（$_会话['list']）；

这里是获取帖子的单循环递归
另一个递归循环显示在列表结果中
保护递归（最多40级帖子）
完全可行代码 $database用于全局避免大堆栈 （我添加了一个（字符串）字段注释，您可以删除或替换它，这是出于测试目的）

保险商实验室{
左边框：实心1px灰色；
边缘顶部：1米；
}
ul span.bold{
字体大小：粗体；
}
POST测试

您是否只有一条注释为0的记录？否，可以有多条注释为0的父记录。比如说某人发布了一段视频。直接对发布的注释将位于父项=0处。对评论的回复将具有parent=评论\u id。。。启用嵌套或分层答复。不太有效。向后并缺少后续级别，但不完全正确。结果是：230:{0:'235'，1:'231}，236:{}，237:{0:'291'，1:'238}，240:{0:'290}，241:{0:'292'，1:'289'，2:'283}，244:{0:'304'，1:'293'，2:'288:'284'，6:'282'，7:'281'，8:'279}，294:{295 0:'296}

$_SESSION['list']=array();
//get all comments and descendants for post id.  First get parents at = 0, then recurse through children/descendants
function get_comment_list($db,$post_id) {  
        $comment_array = array();
        $sql = "SELECT comment_id FROM comments WHERE parent = 0 AND _post_id=".$post_id." "."ORDER BY dateTime DESC";
        $result = $db->query($sql); 
        $q = $result->fetchAll(PDO::FETCH_COLUMN, 0);//one level array with '0' parameter   
        foreach($q as $parent){
            //echo $parent;echo '<br>';//first level parent comment
            $_SESSION['list'][] = $parent;//store comment_id's
            get_descendants($db,$parent);    
        }    
    return $_SESSION['list'];
}
//get all descendants of parent level comments
function get_descendants($db,$parent){
    $sql = "SELECT comment_id FROM comments WHERE parent = $parent ORDER BY dateTime DESC";
    $result = $db->query($sql);
    $q = $result->fetchAll(PDO::FETCH_COLUMN, 0);//one level array with '0' parameter   
    foreach($q as $item){
        //echo '&nbsp;&nbsp;'.$item;echo '<br>';
        $_SESSION['list'][]=$item;//store comment_id's
        get_descendants($db,$item);
    }
}
$post_id = 199;
$comment_list = get_comment_list($db,$post_id);
print_r($comment_list);
unset($_SESSION['list']);

<html>

 <head>
     <style>
         ul {
             border-left:solid 1px gray;
             margin-top:1em;
         }

         ul span.bold {
             font-weight:bold;
         }
     </style>
 </head>   

 <body>



<H1>POSTs TEST</H1>

<?php

// get informations
// @PARAM $startParent = first id parent, 
// @PARAM $whereToAppend = $root = array to fill
// @PARAM $level = increase each recursion, stop if greater than 40
function getComments($startParent,&$whereToAppend,$level) {

  // use global database handler
  global $bdd;  

  // secure infinite loop !
  if ($level>40) { return; }

  // get alls post with id_parent=$startParent 
  $i=0;
  // NOTE you can append a SORT tag, DESC if you want etc...
  $sql="select comment_id, parent, comment from comments where parent=$startParent";
  $result = $bdd->query($sql);
  // prepare a structure to store one post
  while ($donnees = $result->fetch()) {
   $datas=array('comment_id'=>$donnees['comment_id'],
                 'parent'=>$donnees['parent'],
                 'comment'=>$donnees['comment']
                 );

   // for more readability  
   // this post has a id            
   $id=$datas['comment_id'];

   // store the post in three
   $whereToAppend[$i]['id']=$id;
   $whereToAppend[$i]['datas']=$datas;
   $whereToAppend[$i]['sub']=array();

   // next post (always for post who has a id_parent : see parameters)
   $i++;
  }

  // now recursion...
  foreach ($whereToAppend as $k=>$d) {
        // get posts who have parent_id=id of the post found  
        getComments($d['id'],$whereToAppend[$k]['sub'],$level+1);
  }

  return ;

}


// used to show result 
// @param $start=array to iterate
// @param $level=level , always 0 at first call
function iterate($start,$level=0) {
    echo('<ul>');
    foreach ($start as $k=>$element) {
        echo("<li>");
        echo ("comment_id=<span class='bold'>{$element['datas']['comment_id']}</span><br>");
        echo ("id parent=<span class='bold'>{$element['datas']['parent']}</span><br>");
        echo ("comment=<span class='bold'>{$element['datas']['comment']}</span><br>");
        iterate($element['sub'],$level+1);
        echo("</li>");
    }
    echo('</ul>');
}



// MAIN
$bdd = new PDO('mysql:host=localhost;dbname=test;charset=utf8', 'root', '');

// prepare a array where to get informations
$root=array();

// get informations
// first para 0=> id parent, try with another id parent to get partial tree
// second param $root = array to fill
// third param=0, level 0 = recursion start at 0
getComments(0,$root,0);


// show informations
iterate($root,0);



?>
 </body>
</html>