PHP, how to convert indexed array to associative array easily

You can use PHP array_column() function. For your use case, the second argument should be null to return the full array.

$a = array(
array("id" => 1, "name" => "a1"),
array("id" => 2, "name" => "a2")
);

$b = array_column($a, null, 'name');

and print_r($b) will result in

Array
(
[a1] => Array
    (
        [id] => 1
        [name] => a1
    )

[a2] => Array
    (
        [id] => 2
        [name] => a2
    )

)

You can simply do this

$input = [
    ["id" => 1, "name" => "a1"],
    ["id" => 2, "name" => "a2"]
];

$result = array_merge(
    ...array_map(
        fn($item) => [$item['name'] => $item],
        $input
    )
);

The only solution I see is to loop through the array and create a new array manually.

For example, like this:

$new_array = [];
foreach ($array as $value) 
    $new_array[$value['name']] = $value;