extracting database data as an array for use in PHP class for threaded comments

[terungwa]

I need to set up a threaded comments system in a PHP project and I got this script shown below from http://www.jongales.com/blog/2009/01/27/php-class-for-threaded-comments/#comment-436261

class Threaded_comments
{
    
    public $parents  = array();
    public $children = array();

    /**
     * @param array $comments 
     */
    function __construct($comments)
    {
        foreach ($comments as $comment)
        {
            if ($comment['parent_id'] === NULL)
            {
                $this->parents[$comment['id']][] = $comment;
            }
            else
            {
                $this->children[$comment['parent_id']][] = $comment;
            }
        }        
    }
   
    /**
     * @param array $comment
     * @param int $depth 
     */
    private function format_comment($comment, $depth)
    {   
        for ($depth; $depth > 0; $depth--)
        {
            echo "\t";
        }
        
        echo $comment['text'];
        echo "\n";
    }
    
    /**
     * @param array $comment
     * @param int $depth 
     */ 
    private function print_parent($comment, $depth = 0)
    {   
        foreach ($comment as $c)
        {
            $this->format_comment($c, $depth);

            if (isset($this->children[$c['id']]))
            {
                $this->print_parent($this->children[$c['id']], $depth + 1);
            }
        }
    }

    public function print_comments()
    {
        foreach ($this->parents as $c)
        {
            $this->print_parent($c);
        }
    }
  
}

Here’s the example usage with the data provided as an array:

$comments = array(  array('id'=>1, 'parent_id'=>NULL,   'text'=>'Parent'),
                    array('id'=>2, 'parent_id'=>1,      'text'=>'Child'),
                    array('id'=>3, 'parent_id'=>2,      'text'=>'Child Third level'),
                    array('id'=>4, 'parent_id'=>NULL,   'text'=>'Second Parent'),
                    array('id'=>5, 'parent_id'=>4,   'text'=>'Second Child')
                );

$threaded_comments = new Threaded_comments($comments);

$threaded_comments->print_comments();

I have a sample select query that pulls data from a database and stores the result in the $comments array as shown below. The $comments array is then passed as an argument to the $threaded_comments object:

$sql = 'SELECT * FROM test_comments';
// submit the query and capture the result
$result = $conn->query($sql);
$comments = array();
while ($row = $result->fetch_assoc()) {
    $comments[] = $row;
}

The challenge is that nothing is printed to the screen when I run the script.

Inspection of the comments array with the var_dump function is shown below:

array (size=4)
  0 => 
    array (size=3)
      'id' => string '1' (length=1)
      'parent_id' => string '0' (length=1)
      'text' => string 'comment' (length=7)
  1 => 
    array (size=3)
      'id' => string '2' (length=1)
      'parent_id' => string '0' (length=1)
      'text' => string 'comment' (length=7)
  2 => 
    array (size=3)
      'id' => string '3' (length=1)
      'parent_id' => string '1' (length=1)
      'text' => string 'comment ' (length=
  3 => 
    array (size=3)
      'id' => string '4' (length=1)
      'parent_id' => string '3' (length=1)
      'text' => string 'comment ' (length=

I was wondering if the array format from my select query is the issue? Could anyone provide a clue as to how to fix this?

 

Thanks.

Edited January 11, 2015 by terungwa

[Ch0cu3r]

Comments with parent id of zero needs to be NULL. Change    $comments[] = $row;

 

to

if($row['parent_id'] == 0) 
   $row['parent_id'] = NULL;

$comments[] = $row;