Custom Validation Rules in State and Cities

belongstate.php

<?php

namespace App\V1\User\Rules;

use Illuminate\Contracts\Validation\Rule;
use App\V1\Common\Models\State;
use App\V1\Common\Models\City;

class belongstate implements Rule
{
    /**
     * Create a new rule instance.
     *
     * @return void
     */
    public $stateId;

    public function __construct($stateId)
    {
        $this->stateId = $stateId;
    }

    /**
     * Determine if the validation rule passes.
     *
     * @param  integer  $attribute
     * @param  mixed  $value
     * @return bool
     */
    public function passes($attribute, $value)
    {
        return City::where(['state_id' => $this->stateId, 'id' => $value])->exists();
    }

    /**
     * Get the validation error message.
     *
     * @return string
     */
    public function message()
    {
        return 'The :attribute não pertence ao estado selecionado';
    }
}

UserUpdateRequest.php

<?php

namespace App\V1\User\Requests;

use Illuminate\Foundation\Http\FormRequest;
use App\V1\User\Rules\belongstate;

class UserUpdateRequest extends FormRequest
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize()
    {
        return true;
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        return [
            'first_name' => 'required|string',
            'last_name'  => 'string|nullable',
            'password'   => 'min:6|sometimes',
            'state_id'   => 'integer|nullable|exists:states,id',
            'city_id'    =>  ['integer', 'nullable', new belongstate(request()->state_id)],
        ];
    }
}