PHP: Building a hierarchistic array structure

Question

I'm having some problems building an hierarchistic array structure - I have almost got it done, but there's something unexplained that makes my array look weird which I hoped you could help me with.

The tree structure is:

root
|data
|-children
|--data
|--children
|---data
|---children

Any child can have any number of children and each child can have any number of parents.

I have a function that builds the tree:

private function build_tree($rows,$parent) {
    $i = 0;
    $response -> result = array();
    $result = array();
    $leaf = false;

    foreach($rows as $row) {
        if($row['parent_id'] == $parent) {
            $leaf = is_null($row['treeDef']) ? false : true;
            $workingSet = array_merge($result,array(                
                'id' => (int)$i, 
                'parent_id' => (int)$row['parent_id'], 
                'child_id' => (int)$row['id'], 
                'name' => (string)$row['resourceName'], 
                'updated' => strtotime($row['updated']), 
                'purchasedUnit' => (string)$row['purchasingUnit'], 
                'purchasedCost' => (double)$row['purchasingCosts'], 
                'purchasedDiscount' => (double)$row['discount'], 
                'estimateUnit' => (string)$row['estimatingUnit'], 
                'profitAddOn' => (string)$row['profitAddOn'], 
                'landedCost' => (double)$row['landedCost'], 
                'unitCorrelation' => (double)$row['unitCorrelation'], 
                'leadTime' => (string)$row['leadTime'], 
                'ResourceClassShortname' => (string)$row['ResourceClassShortname'], 
                'supplierName' => (string)$row['nameSupplier'],
                'iconCls' => (string)$row['typeIcon'],
                'leaf' => $leaf
            ));
            $hasChildren = $this->Resource_model->has_children($rows,$row['id']);
            if ($hasChildren->check) {
                if (!$leaf) {
                    for($j=0; $j <= ($hasChildren -> rows); $j++) {
                        $parentArray = $workingSet;
                        $childArray = $this -> Resource_model -> build_tree($rows,$row['id']);
                        $workingSet = array_merge($parentArray,array('children' => $childArray -> result));
                    }
                } 
            }
            $result[$i] = $workingSet;
            $i++;
        }
    }

    $response -> result = $result;
    $response -> rows = $i; 
    return $response;
}

Which produces this JSON:

PrintScreen

Big picture

Every item that has 2 children (or more? - no test values) gets the first item like it should be, but the second item contains the first item as well - duplicating all the results.

Any help appreciated.

shadyyx · Accepted Answer · 2012-06-18 08:28:29Z

1

Instead of array_merge use array_push - this will add the children subarray instead of trying merging it with the one already existing...

It's in this part of code (already edited):

        $hasChildren = $this->Resource_model->has_children($rows,$row['id']);
        if ($hasChildren->check) {
            if (!$leaf) {
                for($j=0; $j <= ($hasChildren->rows); $j++) {
                    $parentArray = $workingSet;
                    $childArray = $this->Resource_model->build_tree($rows,$row['id']);
                    $workingSet = array_push($parentArray,array('children' => $childArray->result));
                }
            } 
        }

answered Jun 18, 2012 at 8:28

shadyyx

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3 Comments

GauteR Over a year ago

I have some problems implementing this: A PHP Error was encountered Severity: Warning Message: array_push() expects parameter 1 to be array, integer given

GauteR Over a year ago

Adding print_r($parentArray); and print_r($childArray); both prints array structures.

shadyyx Over a year ago

Then how it is possible that the error says the $parentArray is integer? Try to var_dump($parrentArray); for all loops and recurses... Somewhere there must be a point when $parentArray becomes an integer...

GauteR · Accepted Answer · 2012-06-18 09:17:13Z

Made it work, here's the final code:

private function build_tree($rows,$parent) {
    $i = 0;
    $response -> result = array();
    $result = array();
    $leaf = false;
    $newArray = array();

    foreach($rows as $row) {
        if($row['parent_id'] == $parent) {
            $leaf = is_null($row['treeDef']) ? false : true;
            $newArray = array(              
                'id' => (int)$i, 
                'parent_id' => (int)$row['parent_id'], 
                'child_id' => (int)$row['id'], 
                'name' => (string)$row['resourceName'], 
                'updated' => strtotime($row['updated']), 
                'purchasedUnit' => (string)$row['purchasingUnit'], 
                'purchasedCost' => (double)$row['purchasingCosts'], 
                'purchasedDiscount' => (double)$row['discount'], 
                'estimateUnit' => (string)$row['estimatingUnit'], 
                'profitAddOn' => (string)$row['profitAddOn'], 
                'landedCost' => (double)$row['landedCost'], 
                'unitCorrelation' => (double)$row['unitCorrelation'], 
                'leadTime' => (string)$row['leadTime'], 
                'ResourceClassShortname' => (string)$row['ResourceClassShortname'], 
                'supplierName' => (string)$row['nameSupplier'],
                'iconCls' => (string)$row['typeIcon'],
                'leaf' => $leaf
            );

            $hasChildren = $this -> Resource_model -> has_children($rows,$row['id']);
            if ($hasChildren->check) {
                for($j=0; $j <= ($hasChildren -> rows); $j++) {
                    $childArray = $this -> Resource_model -> build_tree($rows,$row['id']);
                    $newArray = array_merge($newArray, array('children' => $childArray -> result));
                }
            }
            $result[$i] = $newArray;
            $i++;
        }
    }

    $response -> result = $result;
    $response -> rows = $i; 
    return $response;
}

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