Game-Jaming/Backend/Controllers/FileHandler/GetGameData.php

<?php
require_once "../../../bootstrap.php";

use \Backend\Models\GameData;
use \Backend\Models\Group;
use Backend\Models\Registration;

if (isset($_GET['gameDataId'])) {
    $openGameDataStream = GameData::find($_GET['gameDataId']);
} elseif (isset($_GET['registrationId'])) {
    $openGameDataStream = Registration::find($_GET['registrationId']);
} elseif (isset($_GET['groupId'])) {
    $registrationIds = Registration::where("group_id", $_GET['groupId'])->pluck("game_data_id")->toArray();
    $openGameDataStream = GameData::whereIn("id", $registrationIds)->get();
} elseif (isset($_GET['gameJamId'])) {
    $gameDataIds = Group::where("game_jam_id", $_GET['gameJamId'])->pluck("game_data_id")->toArray();
    $openGameDataStream = GameData::whereIn("id", $gameDataIds)->get();
} else {
    $openGameDataStream = GameData::all();
}

header("Access-Control-Allow-Methods: GET");
header("Access-Control-Allow-Headers: X-Requested-With, Content-Type, Accept");
header('Content-Type: application/json;charset=UTF-8');
echo json_encode(array('data' => $openGameDataStream->jsonSerialize()));