Dynamic create parent-child relationship array based on another table field values - php

Question

There are 2 arrays Say
1. Groups
$groups = array("user", "account", "client")
2. Results
$results = array(
0 => array(
"user" => "U1",
"account" => "A1",
"client" => "C1"
),
1 => array(
"user" => "U1",
"account" => "A2",
"client" => "C1"
),
0 => array(
"user" => "U1",
"account" => "A3",
"client" => "C1"
),
0 => array(
"user" => "U1",
"account" => "A2",
"client" => "C2"
),
0 => array(
"user" => "U1",
"account" => "A1",
"client" => "C4"
),
0 => array(
"user" => "U1",
"account" => "A1",
"client" => "C5"
),
0 => array(
"user" => "U1",
"account" => "A2",
"client" => "C5"
)
) ;
I want following OUTPUT
$output = array(
"U1" => array(
"A1" => array(C1,C4,C5),
"A2" => array(C1,C2,C5),
"A3" => array(C1)
)
);
The Groups array values are dynamic and may be any order. I want output in order the first value of groups array is the parent element of Output array and second value of group array is the child of parent Output array and so on.

Answer 1

I hope you are using PHP greater or equal to 5.6. There we have ... (splat operator) that will come really handy:
$output = [];
array_map(function (...$keys) use (&$output) {
// Pop the last key, because it is actually a value.
$value = array_pop($keys);
// Prepare "element" to assign the value to using keys and references.
$element = &$output;
while($key = array_shift($keys)) {
if (!isset($element[$key])) {
$element[$key] = [];
}
$element = &$element[$key];
}
$element[] = $value;
}, ...array_map(function ($group) use ($results) {
return array_column($results, $group);
}, $groups));
Here is working demo.
In short, we take advantage of the ability of array_map to take any number of arrays as arguments and traverse them kinda parallelly.

Answer 2

Simply make a foreach loop like this
$new = array();
foreach($results as $key=>$value){
$new[$value["user"]][$value["account"]][] = $value["client"];
}
print_r($new);
live demo : https://eval.in/857969
Using $groups : https://eval.in/857970
$new = array();
foreach($results as $key=>$value){
$new[$value[$groups[0]]][$value[$groups[1]]][] = $value[$groups[2]];
}
Example for multiple user's : https://eval.in/857973
Update
For dynamic groups array : You can use eval if you are not interacting user input here. : https://eval.in/858306