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I have a sample 2d $tasks array which describes a nested structure :

Array
(
    [14] => Array
        (
            [Id] => 14
            [parentId] => null
            [Name] => T1
        )

    [40] => Array
        (
            [Id] => 40
            [parentId] => null
            [Name] => T5
        )

    [41] => Array
        (
            [Id] => 41
            [parentId] => null
            [Name] => T4
        )

    [22] => Array
        (
            [Id] => 22
            [parentId] => 14
            [Name] => T2
        )

    [43] => Array
        (
            [Id] => 43
            [parentId] => 22
            [Name] => T2 child
        )

    [42] => Array
        (
            [Id] => 42
            [parentId] => 14
            [Name] => T3
        )

)

Using the code below I'm transforming this to a proper tree structure :

$sortedArray = array();
// get first level
foreach($tasks as $k => $v){
    if($v['parentId'] == 'null'){
        $sortedArray[$k] = $v;
        unset($tasks[$k]);
    }
}
// sort parents
asort($sortedArray);

function getChildren(array & $a1, array & $a2){
    foreach($a1 as $k => $v){
        findChildren($v, $a2, $k);      
    }
}

function findChildren($rec1, array & $a2, $key){

    foreach($a2 as $k => $v){
        if($rec1['parentId'] == $v['Id']){
            $a2[$k]['children'][$rec1['Id']] = $rec1;
            unset($tasks[$key]);
        } else {
            if (isset($v['children'])){
                findChildren($rec1, $a2[$k]['children'], $key);
            }
        }
    }
}

findChildren($tasks, $sortedArray);

And tho output $sortedArray after running this code looks as follows :

Array
(
    [14] => Array
        (
            [Id] => 14
            [parentId] => null
            [Name] => T1
            [children] => Array
                (
                    [22] => Array
                        (
                            [Id] => 22
                            [parentId] => 14
                            [Name] => T2
                            [children] => Array
                                (
                                    [43] => Array
                                        (
                                            [Id] => 43
                                            [parentId] => 22
                                            [Name] => T2 child
                                        )

                                )

                        )

                    [42] => Array
                        (
                            [Id] => 42
                            [parentId] => 14
                            [Name] => T3
                        )

                )

        )

    [40] => Array
        (
            [Id] => 40
            [parentId] => null
            [Name] => T5
        )

    [41] => Array
        (
            [Id] => 41
            [parentId] => null
            [Name] => T4
        )

)

The problem is, that after calling json_encode on this output array in it's current state I'm getting :

{"14":{"Id":"14","parentId":"null"...

so all nested arrays are inserted with their indexes. I know I can fix the first level using array_values. But is there any simple way of doing this for all levels ? Without it I end up with 'children' being not an array but object which is not satisfying for me.

share|improve this question
 
anyway your array elements will have some indices either initial unordered or ordered (starting from 0) and json_encode will convert them into JSON properties –  haynar Aug 21 '12 at 0:55
2  
you're sure ? using json_encode(array_values($array)) creates a javascript array of objects which is satisfying for me and the indexes are lost which is also fine. –  mike_hornbeck Aug 21 '12 at 6:36
 
yes, you are right :) –  haynar Aug 21 '12 at 14:28

2 Answers

up vote 2 down vote accepted

The code isn't present in your post, but $tasks was created as an associative array. In your example you also iterate through $tasks as you would an associative array:

foreach($tasks as $k => $v){
    ...
}

You need to add children to $tasks as you would with a numeric array; the difference is this:

//associative array
$test = array();
$test["43"] = "hello";
$test["40"] = "hello1";
$test["23"] = "hello2";
print_r($test);

//numeric array
$testb = array(); 
$testb[] = "hello";
$testb[] = "hello1";
$testb[] = "hello2";
print_r($testb);

Live example: http://codepad.org/tsOhX88h

With the numeric array, the top level index (e.g., 14) you've cited as the problem {"14":{"Id":"14","parentId":"null"... is no longer present.

As a simple final step, use this code to push the items from the associative array on to a new numeric array:

$finalArray = array();
foreach ($sortedArray as $key=>$val ){
    $finalArray[] = $sortedArray[$key];
}
print_r($finalArray);

Live example: http://codepad.org/uSGSr1DC

Or you could do it in one shot with array_values:

$finalArray = array();
$finalArray = array_values($sortedArray);
print_r($finalArray);

Live example: http://codepad.org/D7uBSRr8

share|improve this answer
 
ok, but if I won't use assoc array I won't be able to use the code I'm using now to create a tree structure out of a flat array. –  mike_hornbeck Aug 21 '12 at 6:59
up vote 0 down vote

Ok, so I was able to come up with something like this :

function makeIndexed(array & $arr, array & $par = null){
    if(is_null($par)){
        $arr = array_values($arr);
    } else {
        $par['children'] = array_values($arr);
    }

    for($i=0; $i<count($arr); $i++) {   
        $temp = @$arr[$i]['children'];
        if(isset($temp)) {
            makeIndexed($arr[$i]['children'], $arr[$i]);
        }       
    }
}

And now calling makeIndexed($sortedArray); gives me a valid JSON, where 'children' is an array of nodes and not an object. I'm aware of the fact that this code is probably ugly and lacks performance, but at least generates the proper result. If anyone can create something cleaner/shorter I'd gladly mark this as the correct answer.

share|improve this answer
 
Why are you using a for loop? You only need to use array_values once. array_values will return a numeric array that maintains all of your nested structure and removes the top level. Did you look at my example code? codepad.org/pIjA95rG –  Elliot B. Aug 21 '12 at 15:12
 
yes, but this doesn't work. Not sure if you've tested your case with more levels. In my case it only works for the first level. –  mike_hornbeck Aug 21 '12 at 15:19
 
array_values works with additional nested levels: codepad.org/D7uBSRr8 but I've also updated my answer to include a foreach method as well. –  Elliot B. Aug 21 '12 at 16:33

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