Array of objects in php, objects being overwritten, why?

Question

I created a helper to organize the menus returned from the database in a way that is similar to a return of a native method of the framework I am using. The code snippet containing the error is this:

$obj = new \stdClass;
$menu =  array();

for($i=0; $i<count($menus_aceitos_name); $i++){ 
        $obj->name = $menus_aceitos_name[$i];
        $obj->id  = $menus_aceitos_id[$i];
        $menu[$i] = $obj;
    }

I debugged and the expected result would be this But what’s coming in the final variable is this In other words, he’s overwriting the first position with the second, why is this happening? What’s wrong with the code?

Answer 1

How is creating the instance $obj outside the loop, you will have the same reference in all iterations, overriding the old values. This envelope is mirrored into the array $menu because PHP adds to array the object’s own reference and not a copy of it. To solve, you have two solutions: 1) instantiate the object within the loop; 2) insert into the array a copy of the object.

Sample code for solution 1:

$lista = [];

for ($i = 0; $i < 2; $i++) {
  $obj = new stdClass;
  $obj->id = $i;
  $lista[] = $obj;
}

print_r($lista);

^{See working on Repl.it}

Sample code for solution 2:

$obj = new stdClass;
$lista = [];

for ($i = 0; $i < 2; $i++) {
  $obj->id = $i;
  $lista[] = clone $obj;
}

print_r($lista);

^{See working on Repl.it}