Baum\SetMapper::mapTreeRecursive PHP Method

    protected function mapTreeRecursive(array $tree, $parentKey = null, &$affectedKeys = [])
    {
        // For every attribute entry: We'll need to instantiate a new node either
        // from the database (if the primary key was supplied) or a new instance. Then,
        // append all the remaining data attributes (including the `parent_id` if
        // present) and save it. Finally, tail-recurse performing the same
        // operations for any child node present. Setting the `parent_id` property at
        // each level will take care of the nesting work for us.
        foreach ($tree as $attributes) {
            $node = $this->firstOrNew($this->getSearchAttributes($attributes));
            $data = $this->getDataAttributes($attributes);
            if (!is_null($parentKey)) {
                $data[$node->getParentColumnName()] = $parentKey;
            }
            $node->fill($data);
            $result = $node->save();
            if (!$result) {
                return false;
            }
            if (!$node->isRoot()) {
                $node->makeLastChildOf($node->parent);
            }
            $affectedKeys[] = $node->getKey();
            if (array_key_exists($this->getChildrenKeyName(), $attributes)) {
                $children = $attributes[$this->getChildrenKeyName()];
                if (count($children) > 0) {
                    $result = $this->mapTreeRecursive($children, $node->getKey(), $affectedKeys);
                    if (!$result) {
                        return false;
                    }
                }
            }
        }
        return true;
    }