Flat PHP Array to Hierarchy Tree

You should use recursion.

Here an exemple of code:

$datas = array(    array('id' => 1, 'parent' => 0, 'name' => 'Page 1'),    array('id' => 2, 'parent' => 1, 'name' => 'Page 1.1'),    array('id' => 3, 'parent' => 2, 'name' => 'Page 1.1.1'),    array('id' => 4, 'parent' => 3, 'name' => 'Page 1.1.1.1'),    array('id' => 5, 'parent' => 3, 'name' => 'Page 1.1.1.2'),    array('id' => 6, 'parent' => 1, 'name' => 'Page 1.2'),    array('id' => 7, 'parent' => 6, 'name' => 'Page 1.2.1'),    array('id' => 8, 'parent' => 0, 'name' => 'Page 2'),    array('id' => 9, 'parent' => 0, 'name' => 'Page 3'),    array('id' => 10, 'parent' => 9, 'name' => 'Page 3.1'),    array('id' => 11, 'parent' => 9, 'name' => 'Page 3.2'),    array('id' => 12, 'parent' => 11, 'name' => 'Page 3.2.1'),    );function generatePageTree($datas, $parent = 0, $depth=0){    $ni=count($datas);    if($ni === 0 || $depth > 1000) return ''; // Make sure not to have an endless recursion    $tree = '<ul>';    for($i=0; $i < $ni; $i++){        if($datas[$i]['parent'] == $parent){            $tree .= '<li>';            $tree .= $datas[$i]['name'];            $tree .= generatePageTree($datas, $datas[$i]['id'], $depth+1);            $tree .= '</li>';        }    }    $tree .= '</ul>';    return $tree;}echo(generatePageTree($datas));

You can test it at: http://phpfiddle.org/main/code/1qy-5fj

Or if you want the exact format:

function generatePageTree($datas, $parent = 0, $depth = 0){    $ni=count($datas);    if($ni === 0 || $depth > 1000) return ''; // Make sure not to have an endless recursion    $tree = '';    for($i=0; $i < $ni; $i++){        if($datas[$i]['parent'] == $parent){            $tree .= str_repeat('-', $depth);            $tree .= $datas[$i]['name'] . '<br/>';            $tree .= generatePageTree($datas, $datas[$i]['id'], $depth+1);        }    }    return $tree;}

The test: http://phpfiddle.org/main/code/jw3-s1j

You can use FlatToTreeConverter class from Gears helper library:

<?phpnamespace Cosmologist\Gears\Collection;/** * Class able to convert a flat array with parent ID's to a nested tree */class FlatToTreeConverter{    /**     * Convert a flat array with parent ID's to a nested tree     *     * @link http://blog.tekerson.com/2009/03/03/converting-a-flat-array-with-parent-ids-to-a-nested-tree/     *     * @param array  $array           Flat array     * @param string $idKeyName       Key name for the element containing the item ID     * @param string $parentIdKey     Key name for the element containing the parent item ID     * @param string $childNodesField Key name for the element for placement children     *     * @return array     */    public static function convert(array $array, $idKeyName = 'id', $parentIdKey = 'parentId', $childNodesField = 'children')    {        $indexed = array();        // first pass - get the array indexed by the primary id        foreach ($array as $row) {            $indexed[$row[$idKeyName]]                   = $row;            $indexed[$row[$idKeyName]][$childNodesField] = array();        }        // second pass        $root = array();        foreach ($indexed as $id => $row) {            $indexed[$row[$parentIdKey]][$childNodesField][$id] = &$indexed[$id];            if (!$row[$parentIdKey]) {                $root[$id] = &$indexed[$id];            }        }        return $root;    }}

Not sure if you've found an answer yet, but I was looking for the same solution today and finally ended up making my own solution. The below code is the class I just created and it works with PHP arrays and objects and is recursive to an unlimited number of dimensions.

GitHub https://github.com/DukeOfMarshall/PHP-Array-Heirarchy-Display

A simple example of using this code would be:

<?phprequire_once('Arrays.class.php');$display = new Array_Functions();$display->display_hierarchy($multidimensional_array);?>

There are other options that can be set as well, but that was just a straight up heirarchal display of an array or object.

<?phpclass Array_Functions {public $number_of_tabs  = 3; # The default number of tabs to use when branching outprivate $counter            = 0; # The counter to use for the number of tab iterations to use on the current branchpublic $display_square_brackets     = TRUE; public $display_squiggly_brackets = FALSE;public $display_parenthesis           = FALSE;public $display_apostrophe  = TRUE;public $display_quotes        = FALSE;public function __construct(){}/** * Displays the array in an organized heirarchy and even does so recursively *  * $array ARRAY - The array to display in a heirarchy *  * $key_bookends STRING - The character to place on either side of the array key when printed * @@ square - Displays a set of square brackets around the key (DEFAULT) * @@ squiggly - Displays a set of squiggly brackets around the key * @@ parenthesis - Displays a set of parenthesis around the key * @@ FALSE - Turns off the display of bookends around the array key *  * $key_padding STRING - The padding to use around the array key with printed * @@ quotes - Pads the array key with double quotes when printed * @@ apostrophe - Pads the array key with apostrophes when printed (DEFAULT) * @@ FALSE - Turns off the display of padding around the array key *  * $number_of_tabs_to_use INT - The number of tabs to use when a sub array within the array creates a branch in the heirarchy *  */public function display_hierarchy($array, $key_bookends = '', $key_padding = '', $number_of_tabs_to_use = ''){    # Convert the input to a JSON and then back to an array just to make sure we know what we're working with    $array = $this->convert_object_to_array($array);    # If the $array variable is still not an array, then error out.    # We're not going to fool around with your stupidity    if(gettype($array) != 'array'){        echo 'Value submitted was '.strtoupper(gettype($array)).' instead of ARRAY or OBJECT. Only arrays or OBJECTS are allowed Terminating execution.';        exit();    }    # Establish the bookend variables    if($key_bookends != '' || !$key_bookends){        if(strtolower($key_bookends) == 'square'){            $this->display_square_brackets      = TRUE;            $this->display_squiggly_brackets    = FALSE;            $this->display_parenthesis            = FALSE;        }elseif(strtolower($key_bookends) == 'squiggly'){            $this->display_square_brackets      = TRUE;            $this->display_squiggly_brackets    = TRUE;            $this->display_parenthesis            = FALSE;        }elseif(strtolower($key_bookends) == 'parenthesis'){            $this->display_square_brackets      = FALSE;            $this->display_squiggly_brackets    = FALSE;            $this->display_parenthesis          = TRUE;        }elseif(!$key_bookends){            $this->display_square_brackets      = FALSE;            $this->display_squiggly_brackets    = FALSE;            $this->display_parenthesis            = FALSE;        }    }    # Establish the padding variables    if($key_padding != '' || !$key_padding){        if(strtolower($key_padding) == 'apostrophe'){            $this->display_apostrophe = TRUE;            $this->display_quotes       = FALSE;        }elseif(strtolower($key_padding) == 'quotes'){            $this->display_apostrophe = FALSE;            $this->display_quotes       = TRUE;        }elseif(!$key_padding){            $this->display_apostrophe = FALSE;            $this->display_quotes       = FALSE;        }    }           # Establish variable for the number of tabs    if(isset($number_of_tabs_to_use) && $number_of_tabs_to_use != ''){        $this->number_of_tabs = $number_of_tabs_to_use;    }    foreach($array as $key => $value){        $this->insert_tabs();        if(is_array($value)){            echo $this->display_padding($key)." => {<BR>";            $this->counter++;            $this->display_hierarchy($value);            $this->counter--;            $this->insert_tabs();            echo '} <BR>';        }else{            echo $this->display_padding($key)." => ".$value.'<BR>';        }    }}# Inserts tab spaces for sub arrays when a sub array triggers a branch in the heirarchy# Helps to make the display more human readable and easier to understandprivate function insert_tabs(){    for($i=1; $i<=$this->counter; $i++){        for($x=1; $x<=$this->number_of_tabs; $x++){            echo ' ';        }    }}# Takes a PHP object and converts it to an array# Works with single dimension and multidimensional arrayspublic function convert_object_to_array($object){    $object = json_decode(json_encode($object), TRUE);    return $object;}# Sets the displayed padding around the array keys when printed on the screenpublic function display_padding($value){    $default_container = "['VALUE_TO_REPLACE']";    $value = str_replace("VALUE_TO_REPLACE", $value, $default_container);    if($this->display_square_brackets){    }elseif($this->display_squiggly_brackets){        $value = str_replace('[', '{', $value);        $value = str_replace(']', '}', $value);    }elseif($this->display_parenthesis){        $value = str_replace('[', '(', $value);        $value = str_replace(']', ')', $value);    }else{        $value = str_replace('[', '', $value);        $value = str_replace(']', '', $value);    }    if($this->display_apostrophe){    }elseif($this->display_quotes){        $value = str_replace("'", '"', $value);    }else{        $value = str_replace("'", '', $value);    }    return $value;}}?>