einundzwanzig-app/app/Http/Controllers/Api/VenueController.php

<?php

namespace App\Http\Controllers\Api;

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

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

                return $venue;
            });
    }

    /**
     * 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(Lecturer $lecturer)
    {
        //
    }

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

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