einundzwanzig-portal/app/Http/Controllers/Api/CountryController.php

<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\Country;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Http\Request;

class CountryController extends Controller
{
    /**
     * Display a listing of the resource.
     * @return \Illuminate\Http\Response
     */
    public function index(Request $request)
    {
        return Country::query()
                      ->select('id', 'name', 'code')
                      ->orderBy('name')
                      ->when(
                          $request->search,
                          fn(Builder $query) => $query
                              ->where('name', 'ilike', "%{$request->search}%")
                              ->orWhere('code', 'ilike', "%{$request->search}%")
                      )
                      ->when(
                          $request->exists('selected'),
                          fn(Builder $query) => $query
                              ->whereIn('code', $request->input('selected', []))
                              ->orWhereIn('id',
                                  $request->input('selected', [])),
                          fn(Builder $query) => $query->limit(10)
                      )
                      ->get()
                      ->map(function (Country $country) {
                          $country->flag = asset('vendor/blade-country-flags/4x3-'.$country->code.'.svg');

                          return $country;
                      });
    }

    /**
     * Store a newly created resource in storage.
     * @return \Illuminate\Http\Response
     */
    public function store(Request $request)
    {
        //
    }

    /**
     * Display the specified resource.
     * @return \Illuminate\Http\Response
     */
    public function show(Country $country)
    {
        //
    }

    /**
     * Update the specified resource in storage.
     * @return \Illuminate\Http\Response
     */
    public function update(Request $request, Country $country)
    {
        //
    }

    /**
     * Remove the specified resource from storage.
     * @return \Illuminate\Http\Response
     */
    public function destroy(Country $country)
    {
        //
    }
}