带回复的 PHP MySQL 评论系统答案

【问题标题】：PHP MySQL Comment System With Replies带回复的 PHP MySQL 评论系统
【发布时间】：2019-11-27 23:03:23
【问题描述】：

我的代码能够捕获初始评论和第一级回复，但它似乎无法捕获对回复的回复。我知道它需要使用某种形式的递归的不确定代码，但不太确定如何正确实现它。这是我的 phpMyAdmin 表的样子：

id名称评论reply_id
1 BigBadProducer1 我喜欢这个 vst！我用它所有的时间！ 0
2 DrummaBoy504 嘿，我是鼓队的鼓手！ 0
3 Mike Smith 你是如何让 vst 听起来如此出色的... 1
4 BigBadProducer1 是的，我从 YouTube Mike S 那里学会了如何调整它... 3
5 SmoothBeatz3 伙计，我一直在寻找这样的 vst... 0
6 FanBoy123 嘿Drumma，你什么时候发布新的hi... 2
7 Mike Johnson Hey Fanboy123，你为什么这么喜欢 Drum S... 6

代码如下：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
<?php
// Create connection
$conn = new mysqli('localhost', 'root', 'mypassword', 'commentsystem2');

$sql1 = "SELECT * FROM comments WHERE reply_id = 0";
$result1 = mysqli_query($conn, $sql1);

while ($comment = mysqli_fetch_array($result1)) {
    $id = $comment['id'];
    $name = $comment['name'];
    $comment = $comment['comment'];
    
echo '
<div class="comments" style="position:relative; margin:auto; width:500px; border:1px solid black; margin-top:1px;">
<div>'.$name.'</div>
<div>'.$comment.'<br><br></div>
</div>
';

$sql2 = "SELECT * FROM comments WHERE reply_id = $id";
$result2 = mysqli_query($conn, $sql2);
while ($reply = mysqli_fetch_array($result2)) {
$id_reply = $reply['id'];
$reply_name = $reply['name'];
$reply_comment = $reply['comment'];
$reply_id = $reply['reply_id'];


echo '
<div class="replies" style="position:relative; margin:auto; width:500px; border:1px solid black; margin-top:1px;">
<div style="width:80%; text-align:center;">'.$reply_name.' replied to '.$name.'</div>
<div style="width:80%; text-align:center;">'.$reply_comment.'<br><br></div>
</div>
';

 }//end of replies while loop

}//end of comments while loop

?>
</body>
</html>

【问题讨论】：

一些基本思想：递归并不是唯一的方法。查看“物化路径”：您必须重做 reply_id，但这样做的好处可能是值得的。如果您确实选择继续使用递归，则需要采取措施实现更复杂的编码风格。目前，您正在使用一种非常程序化的风格：处理页面呈现中发生的事情。您需要采用更多的 OOP 风格；至少你需要一个调用自身的函数。我建议使用stackoverflow.com/a/58806465/2129574 中的样式
当你得到顶部的逻辑和底部的表示时，那么合并函数进行递归就更容易了。
感谢蒂姆的概念。你有我可以测试的示例或代码 sn-p 吗？我需要将它保存在数据库中，但我愿意尝试你的想法。再次感谢。

标签： php comments system reply

【解决方案1】：

递归

这里是递归解决方案的一个简单示例，使用数组作为数据库查询的模型。

一些重要说明：

注意结构：所有数据获取和操作都是在打印出单个内容之前完成的。
这作为一个对象会好得多，这样可以避免函数内的GLOBAL标签，但这会让你指向那个方向。
递归函数应该总是有一个测试来停止递归，以防万一出现问题。这个例子没有！您可以使用静态变量来计算递归并在达到某个限制时停止。

<?php

// mock data of "select * from comments"
$dbRows = [
  1 => ['name' => 'BigBadProducer1', 'comment' => 'I love this vst! I use it all the time!', 'reply_id' => 0],
  2 => ['name' => 'DrummaBoy504', 'comment' => 'Hey, this is Drumma from Drum Squad!', 'reply_id' => 0],
  3 => ['name' => 'Mike Smith', 'comment' => 'How did you get the vst to sound so good like that...', 'reply_id' => 1],
  4 => ['name' => 'BigBadProducer1', 'comment' => 'Yes, I learned how to tweak it from YouTube Mike S...', 'reply_id' => 3],
  5 => ['name' => 'SmoothBeatz3', 'comment' => 'Dude, Ive been looking for a vst like this for a l...', 'reply_id' => 0],
  6 => ['name' => 'FanBoy123', 'comment' => 'Hey Drumma, when are you going to release a new hi...', 'reply_id' => 2],
  7 => ['name' => 'Mike Johnson', 'comment' => 'Hey Fanboy123, why are you such a fanboy of Drum S...', 'reply_id' => 6],
  ];

// mock data of "select id from comments where reply_id=?"
$children = [];
foreach($dbRows as $id => $row) {
  $reply_id = $row['reply_id'];
  $children[$reply_id][] = $id;
}

// format row into html
function formatRow($row, $reply_name='unknown') {
    $out =<<<FORMATROW
<div class="replies" style="position:relative; margin:auto; width:500px; border:1px solid black; margin-top:1px;">
<div style="width:80%; text-align:center;">{$row['name']} replied to {$reply_name}</div>
<div style="width:80%; text-align:center;">{$row['comment']}<br><br></div>
</div>
FORMATROW;

    return $out;
}

// mock of database CRUD function "select * from comments where id=?"
function find($id) {
    global $dbRows;
    if(array_key_exists($id, $dbRows)) {
        return $dbRows[$id];
    }
}

// mock of database CRUD function "select id from comments where reply_id=?"
function findChildren($id) {
    global $children;
    if($id == 0) { return []; }

    $out = [];
    if(array_key_exists($id, $children)) {

        $out = $children[$id];
    }
    return $out;
}

function getRepliesTo($id) {

    // test to end recursion
    // if(!$id) { return; }

    // get parent name
    $row = find($id);
    $parent_name = $row['name'];

    // start indented list every time a traversal is called
    $out = "<ul>\n";

    // list of child ids. if no children are found, 
    // assigns an empty array so that foreach won't barf
    $children = findChildren($id);

    foreach($children as $cid) {

        // if there are children, capture their reply and then call this same function to get replies to this reply            
        if($reply= find($cid)) {
            $out .= '  <li>' . formatRow($reply, $parent_name);
            $out .= getRepliesTo($cid);
            $out .= "</li>\n";
        }
    }

    $out .= "</ul>\n";
    return $out;
}

// print_r(find(1));
// print_r(findChildren(1));
// print_r(findChildren(2));
// print traverse(1);

$id = 1; // $id = (int)$_GET['id'];

$commentData = find($id);
$replyHtml = getRepliesTo($id);

?>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
  <div class="comments" style="position:relative; margin:auto; width:500px; border:1px solid black; margin-top:1px;">
    <div><?= $commentData['name'] ?></div>
    <div><?= $commentData['comment'] ?><br><br></div>
  </div>
  <?= replyHtml ?>
</body>
</html>

物化路径

另一种方法是使用物化路径查询，这需要对 reply_id 字段稍作更改：

$dbRows = [
  1 => ['name' => 'BigBadProducer1', 'comment' => 'I love this vst! I use it all the time!',               'reply_id' => '/0/1'],
  2 => ['name' => 'DrummaBoy504',    'comment' => 'Hey, this is Drumma from Drum Squad!',                  'reply_id' => '/0/2'],
  3 => ['name' => 'Mike Smith',      'comment' => 'How did you get the vst to sound so good like that...', 'reply_id' => '/0/1/3'],
  4 => ['name' => 'BigBadProducer1', 'comment' => 'Yes, I learned how to tweak it from YouTube Mike S...', 'reply_id' => '/0/1/3/4'],
  5 => ['name' => 'SmoothBeatz3',    'comment' => 'Dude, Ive been looking for a vst like this for a l...', 'reply_id' => '/0/5'],
  6 => ['name' => 'FanBoy123',       'comment' => 'Hey Drumma, when are you going to release a new hi...', 'reply_id' => '/0/2/6'],
  7 => ['name' => 'Mike Johnson',    'comment' => 'Hey Fanboy123, why are you such a fanboy of Drum S...', 'reply_id' => '/0/2/6/7'],
  ];

想找到 2 的所有后代吗？ select * from comments where reply_id like '/0/2%'

【讨论】：