php层次结构评论系统

Question

我想做discus/reddit/之类的评论系统，我的评论数据库中有一个“id_answer”（默认设置为0）字段，当用户回答另一个评论时，该字段是父评论的“id”。

我在数组中有线程的注释，但我不知道如何过滤每个循环以获得如下内容：

评论等级 1（$array[id_answer] 为 0）

------ 评论级别 2（$array[id_answer] 是 id_of_level_one_comment）

---------------评论3级...

Answer 1

使用数据库中的三个字段；

• “id”，对于每个评论都是唯一的
• “parent_id”，可以是 0（顶级评论）或父评论的“id”
• “thread_id”，这是您正在评论的任何内容的 id

假设您要显示id为“123”的新闻文章的评论树

当从mysql中选择时，选择具有此thread_id的所有内容：

SELECT id, parent FROM comments WHERE thread_id = 123

然后您应该预先解析数组以将子评论提供给其父母，并使用递归显示来显示每个评论评论及其子列表。

例如：

// getting the comments from mysql, I'm obviously not bothering
//   to check the return value, but in your code you should do it
$result = mysqli_query("SELECT id, parent FROM comments WHERE thread_id = 123");

$comments = array();
while ($row = mysqli_fetch_array($result)) {
  $row['childs'] = array();
  $comments[$row['id']] = $row;
}

// This is the array you get after your mysql query
// Order is non important, I put the parents first here simply to make it clearer.
/*
$comments = array(
    // some top level (parent == 0)
    1 => array('id' => 1, 'parent' => 0, 'childs' => array()),
    5 => array('id' => 5, 'parent' => 0, 'childs' => array()),
    2 => array('id' => 2, 'parent' => 0, 'childs' => array()),
    10 => array('id' => 10, 'parent' => 0, 'childs' => array()),
    // and some childs
    3 => array('id' => 3, 'parent' => 1, 'childs' => array()),
    6 => array('id' => 6, 'parent' => 2, 'childs' => array()),
    4 => array('id' => 4, 'parent' => 2, 'childs' => array()),
    7 => array('id' => 7, 'parent' => 3, 'childs' => array()),
    8 => array('id' => 8, 'parent' => 7, 'childs' => array()),
    9 => array('id' => 9, 'parent' => 6, 'childs' => array()),
);
*/

// now loop your comments list, and everytime you find a child, push it 
//   into its parent
foreach ($comments as $k => &$v) {
  if ($v['parent'] != 0) {
    $comments[$v['parent']]['childs'][] =& $v;
  }
}
unset($v);

// delete the childs comments from the top level
foreach ($comments as $k => $v) {
  if ($v['parent'] != 0) {
    unset($comments[$k]);
  }
}

// now we display the comments list, this is a basic recursive function
function display_comments(array $comments, $level = 0) {
  foreach ($comments as $info) {
    echo str_repeat('-', $level + 1).' comment '.$info['id']."\n";
    if (!empty($info['childs'])) {
      display_comments($info['childs'], $level + 1);
    }
  }
}

display_comments($comments);

这给出了以下结果：

- comment 1
-- comment 3
--- comment 7
---- comment 8
- comment 5
- comment 2
-- comment 6
--- comment 9
-- comment 4
- comment 10

我将 ORDER BY 等留给您，因为它不会造成任何问题。