Arr::add() use Laravel 11.x

In Laravel 11.x, you can use `Arr::add()` from the Illuminate\Support\Arr class to add a key-value pair to an array only if the key does not already exist.

Syntax of `Arr::add()`

Arr::add(array $array, string $key, mixed $value): array

If the key exists, the original array is returned unchanged.
If the key does not exist, the key-value pair is added.

Example Usage in Laravel 11.x

1. Basic Example

use Illuminate\Support\Arr;
$array = ['name' => 'John'];
// Add 'email' key only if it does not exist
$result = Arr::add($array, 'email', 'john@example.com');
print_r($result);

Output:-

Array
(
[name] => John
[email] => john@example.com
)

2. If the Key Already Exists

use Illuminate\Support\Arr;
$array = ['name' => 'John', 'email' => 'old@example.com'];
// Attempt to add 'email' key
$result = Arr::add($array, 'email', 'new@example.com');
print_r($result);

Output:-

Array
(
[name] => John
[email] => old@example.com
)

3. Adding Nested Keys:-

You can use dot notation to add keys inside nested arrays.

use Illuminate\Support\Arr;
$array = ['user' => ['name' => 'Alice']];
$result = Arr::add($array, 'user.email', 'alice@example.com');
print_r($result);

Output:

Array
(
[user] => Array
(
[name] => Alice
[email] => alice@example.com
)
)