Recursive loop for category

Question

I'm trying to implement a category system on my website. The problem is that a category can have child. So far, my table category looks like that :

id, name, parent_id

So far, I made a loop, but it only works for 2 levels. Here is my code :

for($i=0;$i<count($data);$i++){
    $tree[$data[$i]->name] = array();
    for($j=0;$j<count($data);$j++){
        if($data[$j]->parent_id == $data[$i]->id){
            $tree[$data[$i]->name][] = $data[$j]->name;
        }
    }
}

It return me an array as it :

Array
(
    [0] => Array
        (
            [1] => Cat1
            [children] => Array
                (
                    [12] => sub cat 1
                    [13] => sub cat 2
                    [14] => sub cat 3
                )

        )

    [1] => Array
        (
            [2] => Cat2
        )

    [2] => Array
        (
            [3] => Cat3
        )
)

How can I make it efficient and recursive to have something more like :

Array
(
    [0] => Array
        (
            [1] => Cat1
            [children] => Array
                (
                    [12] => sub cat 1
                    [13] => sub cat 2
                    [14] => sub cat 3
                        [children] => Array
                            (
                                [1] => sub sub cat 1
                            )
                )

        )

    [1] => Array
        (
            [2] => Cat2
        )

    [2] => Array
        (
            [3] => Cat3
        )
)

Thanks for your help

EDIT

I'm working on Zend, and it return me the data as it :

Zend_Db_Table_Rowset Object
(
    [_data:protected] => Array
        (
            [0] => Array
                (
                    [id] => 1
                    [name] => Cinema
                    [type] => category
                    [slug] => cinema
                    [parent_id] => -1
                )

            [1] => Array
                (
                    [id] => 2
                    [name] => Horror
                    [type] => category
                    [slug] => horror
                    [parent_id] => 1
               )

score 2 · Answer 1 · answered Apr 04 '13 at 08:58

2

If you want to apply this type of structure best to use child in other table with parent id as a foreign key. so with that u can have recursive category posting. so the table structure will be like this

ch_id, parent_id, child

answered Apr 04 '13 at 08:58

Shwet

1,848
1
24
35

Hi, yes I know, but unfortunately, I don't have the choice, I have to use it the way it is now – lkartono Apr 04 '13 at 09:04
up to which level u want nested category??????if u have 2-3 layer than your code is perfact with one more for loop... – Shwet Apr 04 '13 at 09:06
There's no limit of nested level. Should I just use 2 tables in that case? – lkartono Apr 04 '13 at 09:31
than it will be better to use two tables...so that query will be shared on both tables and will make some happiness for u – Shwet Apr 04 '13 at 11:07

score 0 · Answer 2 · edited May 23 '17 at 10:25

0

You should check out Nested Sets, a methodology to store and retrieve date trees in/out of relational databases (what in fact your categories are). For this, you have to adapt your database scheme a little bit (as described in the link or in the several tutorials about nested sets). For PHP, there are several libraries providing Nested Set capabilities, for instance this list.

edited May 23 '17 at 10:25

Community

1
1

answered Apr 04 '13 at 08:58

strauberry

4,189
5
34
50

scones · Answer 3 · 2013-04-04T09:40:46.127

0

This should help you out. It Iterates over every member of the array and checks it's position in the tree structure per level and dependency.

function get_children($data, $parent_id = false) {
  $result = array();
  foreach ($data as $i => $content) {
    if ($parent_id != false && $content['id'] != $parent_id)  # other levels
      continue;
    if ($parent_id === false && !empty($content['parent_id'])) # top level
      continue;

    $leaf = array(
      'id' => $content['id'],
      'parent_id' => $content['parent_id'],
      'name' => $conten['name']
    );
    $leaf['children'] = get_children($data, $leaf['id']);
    $result[$leaf['id']] = $leaf;
  }
  return $result;
}

$result =  get_children($data);
print_r($result);

Edit: bug fixes

edited Apr 04 '13 at 09:40

answered Apr 04 '13 at 09:06

scones

3,317
23
34

Hi, thanks but still not working but I'm closer to solve it now. Actually this line `if ($content['id'] == $data['parent_id']) {` can't work since $data is an array of all categories so I can't access by $data['parent_id'] directly – lkartono Apr 04 '13 at 09:22
@user1965817 ah, you're right, wait i fix that. will be a tad bit slower though – scones Apr 04 '13 at 09:24
Hmm, yeah you were right, it's too slow. I've got `Fatal error: Allowed memory size`, so I may go for 2 tables in that case, will be maybe much more simple. Thought? – lkartono Apr 04 '13 at 09:30
@user1965817 allowed memory size should not kick in. at least not if you just have a few thousand categories. This just means, that one of the break conditions is not working. Is you data cyclical? – scones Apr 04 '13 at 09:41

Recursive loop for category

3 Answers3