dou-smallapp/app/Http/Controllers/Api/AdController...

<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Service\AdService;
use Illuminate\Http\Request;
use Illuminate\Validation\Rule;

class AdController extends Controller
{
    public function getAdPlacement(Request $request) {
        $validator = \Validator::make($request->all(),[
            'app_id' => 'required|string',
            'type'   => ['nullable', Rule::in([1, 2, 3, 4, 5, 6])],
        ]);

        if ($validator->fails()) {
            return self::returnValue($validator->getMessageBag(), 1102);
        }

        $appId = $request->input('app_id');
        $type = $request->input('type', 2);

        $data = AdService::getAdPlacement($appId, $type);
        return self::returnValue($data);
    }
}