Question

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.

Answer 1

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