How to use array_map with reset callback in php 8-CodePudding

I have a function that work good in php 7 but in php 8.0.11 has warning

$orders->result = array_map('reset', $orders->result);

E_WARNING: reset(): Argument #1 ($array) must be passed by reference, value given in

Of course, I can use this code instead that but maybe slower than array_map

foreach ($orders->result as $item)
       $result[$item[0]['order_id']] = $item[0];

Edit: before foreach or array_map the output like this

    Array
(
    [0] => Array
        (
           [order_id] => 41111909
           [shop_id] => 34277
           [user_id] => 42363
           [status_id] => 4
         )
)

after use foreach output like this

Array
(
    [41111909] => Array
        (
           [order_id] => 41111909
           [shop_id] => 34277
           [user_id] => 42363
           [status_id] => 4
         )
)

How to solve it ?

CodePudding user response：

The simplest replacement is to make an arrow function (single-expression closure) to get the element for you.

If the arrays are plain lists, so that you're always getting element 0, that's as simple as:

$orders->result = array_map(fn($item) => $item[0], $orders->result);

Another alternative in this case is array_column:

$orders->result = array_colum($orders->result, 0);

If you have other keys, you could use either reset or array_key_first in the callback instead:

$orders->result = array_map(fn($item) => $item[array_key_first($item)], $orders->result);

(I suspect array_key_first will be slightly more efficient, since it doesn't need to manipulate the internal array pointer.)

CodePudding user response：

It's not entirely clear what you're trying to do, but it seems like you are trying to get the first value from nested arrays. You should be able to use a function:

$orders->result = array_map(function($v) { return reset($v); }, $orders->result);

You may also try using current if it does what you need as it doesn't take a reference and the array pointer should already be reset by array_map:

$orders->result = array_map('current', $orders->result);