create multidimensional array from json object list - php

Question

I have a json feed that is more or less a list of objects
each has it's own id and idParent. objects that have idParent of null are the base parent elements. What I'm trying to achieve is to make a proper multidimensional array like a tree view. Keep in mind that children can have children too.
{
"obj1":{
"idParent":null,
"id":"parent1"
},
"obj2":{
"idParent":null,
"id":"parent2"
},
"obj3":{
"idParent":null,
"id":"parent3"
},
"obj4":{
"idParent":null,
"id":"parent4"
},
"obj5":{
"idParent":null,
"id":"parent5"
},
"obj6":{
"idParent":"parent1",
"id":"layer1-1"
},
"obj7":{
"idParent":"parent1",
"id":"layer1-2"
},
"obj8":{
"idParent":"parent2",
"id":"layer1-3"
},
"obj9":{
"idParent":"parent4",
"id":"layer1-4"
},
"obj10":{
"idParent":"parent3",
"id":"layer1-5"
},
"obj11":{
"idParent":"layer1-1",
"id":"layer2-1"
},
"obj12":{
"idParent":"parent5",
"id":"layer2-2"
},
"obj13":{
"idParent":"layer1-4",
"id":"layer2-3"
},
"obj14":{
"idParent":"layer1-5",
"id":"layer2-4"
},
"obj15":{
"idParent":"layer1-5",
"id":"layer2-5"
}
}
I've managed to filter out the root parents but after that I fail very bad
The first function does filter out the root parent nodes with idParent of null.
function decodeData($data) {
global $out;
foreach ($data as $key => $obj) {
if (is_array($obj)) {
foreach ($obj as $prop => $value) {
if ($prop == 'idParent') {
if($value == null) {
array_push($out, $obj);
unset($data[$key]);
}
}
}
}
}
if (count($data) > 0) {
decodeData($data);
} else {
echo json_encode(array('length'=>count($data)));
}
}
And this is what I'm experimenting on with no result
function decodeData($arrays) {
global $out;
foreach ($arrays as $array_name => $arr) {
foreach ($arr as $arr_prop => $arr_val) {
if ($arr_prop == 'idParent' && $arr_val == null) { // we found root parents
array_push($out, $arr);
unset($arrays[$array_name]); //remove array from the list
} else { // check if idParent is inside out
foreach ($out as $out_arr_name => $out_arr) { // iterate through out arrays
foreach ($out_arr as $out_arr_prop => $out_prop_val) { //
if ($out_arr_prop == 'id' && $arr_prop == 'idParent' && $out_arr_val == $arr_val) {
array_push($out_arr['children'], $obj);
unset($arrays[$array_name]);
}
}
}
}
}
}
if (count($arrays) > 0) {
decodeData($arrays);
} else {
echo json_encode(array('length'=>count($arrays)));
}
}
If anyone could provide some help I would really appreciate it.

Answer 1

I couldn't figure out what output do you want, so I just made a simple tree structure:
$data = json_decode( $your_json_string );
// Store each element in a lookup table indexed by element id
// 0th pass: put a fake root element there
$by_id = array(
'*' => new stdclass
);
// First pass: put each element into there
foreach( $data as $o ) $by_id[ $o->id ] = $o;
// Second pass: add each element into its parent's children array
foreach( $data as $o ){
$pid = $o->idParent ? $o->idParent : '*';
$p = $by_id[ $pid ];
$p->children[] = $o;
}
// Trash everything else, we start from the (fake) root element:
$tree = $by_id['*']->children;
/**** REVERSE ****/
$todo = $tree;
$json = array();
while( $todo ){
$o = array_shift( $todo );
if( isset( $o->children )){
$todo = array_merge( $todo, $o->children );
unset( $o->children );
}
$json[] = $o;
};
echo json_encode( $json );
The result:
http://codepad.viper-7.com/V7PjDh