How to validate email as unique while updating data using laravel form request?

I'm using form request to validate data into update method. I'm trying to validate email as a unique value expect requested user email like this

 public function rules() {
    $user = $this->user();
    return [
        'name'       => 'required|max:255|string',
        'email'      => 'required|email|max:255|unique:users,email,'.$user->id,
        'restaurant' => 'required',

    ];
}

But it doesn't work, how to access requested user id into form request?

I will assume that you are posting a user object, where id is included in your $request data.

In case you are storing a new record and email needs to be available, you can use:

use Illuminate\Validation\Rule;
...
public function rules() {
    return [
        'name'  => 'required|max:255|string',
        'email' => ['required', 'email', 'max:255', Rule::unique('users')],
        'restaurant' => 'required',
    ];
}

If you want to ignore your user->id, because you are updating your record and obviously the email is taken by the user:

use Illuminate\Validation\Rule;
...
public function rules() {
    return [
        'name'  => 'required|max:255|string',
        'email' => ['required', 'email', 'max:255', Rule::unique('users')->ignore($this->id)],
        'restaurant' => 'required',
    ];
}