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I need to sort an array of objects for a forum program with multiple comparisons. Each post (main thread or reply) is an instance of a class Post. I need to sort the main threads by their timeLastChanged property (for bumping) and then sort the replies underneath them by their timeStarted property (oldest first). My goal was to sort the array in the exact order it would be displayed in the forum table. Simply, sorted and displayed like this: 

- Main thread
   - Reply
      - Reply
   - Reply
   - Reply
      - Reply
         - Reply
- Main thread

etc.
I've looked at usort and the like but I can't figure how the comparison functions would work to do this. Oh, and each object has a property isReply that is set to 0 if it isn't a reply and set to the thread ID of the post it is a reply of, if it is a reply. Each object has a property TID which is its thread ID (unique). I also have a property called numReplies that shows how many direct replies a message has (and then, of course, replies would have their own numReplies that show how many replies are assigned to that reply, etc).

I've got the displaying part down and the grabbing the info from the database, I'm just not sure of the most efficient way of sorting it. Thanks for any help.

Edit: here is the code I have that starts the class, I excluded the part where I grab the data from the database, but just know that all the applicable instances of Post are assigned to their respective array of objects (replies are in replyObjs, mains are in mainsObjs, etc):

class Category {

    public $title;
    public $majCatID;
    public $catID;
    public $modLevel;
    public $postingLevel;
    public $hostedByUID;
    public $order;
    public $shortName;
    public $info;
    public $stickyObjs;
    public $mainsObjs;
    public $replyObjs;
    public $orderedObjs;
    private $database;

    public function __construct($catID) {
        $this->database = new TBDatabase;
        $result = $this->database->getIntRow(CAT_TABLE, 'catID', $catID);
        $row = $this->database->fetchAssoc($result);
        $this->title = $row['title'];
        $this->majCatID = $row['majCatID'];
        $this->catID = $row['catID'];
        $this->modLevel = $row['modLevel'];
        $this->postingLevel = $row['postingLevel'];
        $this->hostedByUID = $row['hostedByUID'];
        $this->order = $row['order'];
        $this->shortName = $row['shortName'];
        $this->info = $row['info'];
        }
    public function sortPosts() {
        $table = $this->shortName."_threads";
        $this->getStickyObjs();
        $numStickies = count($this->stickyObjs);
        $this->getMainObjs();
        $numMains = count($this->mainsObjs);
        $this->getReplyObjs();
        $numReplies = count($this->replyObjs);
        }
share|improve this question

1 Answer 1

up vote 0 down vote

You are sorting an array of objects, so the PHP array functions are not really going to help you unless you want to sort by the array keys.

You'll have to loop over the array of objects and access the objects properties and rebuild your array in the order you want. Without seeing some of your code, it's not really possible to give more detail.

As you are pulling the data from the database, it's probably best to do the sorting there.

If you have a class "Article" then it can have a method "getComments" which may do the database calls directly or involve some other classes/methods to retrieve the comments for that article. Though, sorting in the database is probably the best all round, as you may as well sort them while retrieving them. That's what databases do.

Here is an air code example. It's a recursive function. So be careful.

public function getComments($id, $sort)
{
    $sorted = array();
    $comments = $this->getChildren($id, $sort); // make getChildren return null if no children records.
    if (!is_null($comments) && count($comments) > 0)
    {
        foreach ($comments as $comment)
        {
            $sorted[$comment['id']] = $comment;
            $sorted[$comment['id']]['children'] = $this->getComments($comment['id'], $sort);
        }
    }
    else
    {
        $sorted = $comments;
    }
    return $sorted;
}
share|improve this answer
    
I'll edit the question with my current code minus the failed attempts at sorting it myself. –  Adam Mar 18 '11 at 1:41
    
I don't see any code. Are you coding in PHP? Do you have a property "parentID" or some such thing? –  d-_-b Mar 18 '11 at 1:44
    
I just posted the code I have so far, it's just a basic class start and some database calls so far, the sorting attempts from earlier I left out. Yes, I have a parentID property, it is called isReply which is set to 0 if it isn't a reply and if it is a reply, it is set to the thread ID (TID) of the direct parent message. –  Adam Mar 18 '11 at 1:47
    
Oh, there is the code now. –  d-_-b Mar 18 '11 at 1:47
    
By the way, the "getStickyObjs" and "getMainsObjs" calls are just functions I left out because they just simply grab the messages from the database according to if they are a sticky, main, or reply and instantiate a Post object for each based on their info and apply it to one of the three arrays of objects (stickyObjs, mainsObjs, or replyObjs). –  Adam Mar 18 '11 at 1:49

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