How to use Eloquent (from Laravel) inside Wordpress

Car.php

<?php // File location: /wp-content/themes/my-theme/src/Models/

namespace App\Models;

use Illuminate\Database\Eloquent\Model as Eloquent;

class Car extends Eloquent
{
    protected $table = 'cars';
    protected $primaryId = 'id';
}

composer.json

{
  "require": {
    "illuminate/database": "~5.0.0"
  },
  "autoload": {
    "psr-4": {
      "App\\": "wp-content/themes/my-theme/src/"
    }
  },
}

functions.php

<?php // File location: /wp-content/themes/your-theme/

require __DIR__.'/../../../vendor/autoload.php'; // include composer inside Wordpress

/*
 * Configure Eloquent (called Capsule when used alone)
 */
 
$capsule = new \Illuminate\Database\Capsule\Manager;

$capsule->addConnection([
    'driver'    => 'mysql',
    'host'      => 'localhost',
    'database'  => 'database',
    'username'  => 'root',
    'password'  => 'password',
    'charset'   => 'utf8',
    'collation' => 'utf8_unicode_ci',
    'prefix'    => '',
]);

$capsule->setEventDispatcher(new \Illuminate\Events\Dispatcher(new \Illuminate\Container\Container));
$capsule->setAsGlobal();
$capsule->bootEloquent();

// other code in functions.php here

page.php

<?php // File location: /wp-content/themes/my-theme/

$cars = App/Models/Car::all(); ?>

<!-- HTML or PHP code -->

<?php foreach ($cars as $car): ?>
    <h1><?php echo $car->model_name ?></h1>
<?php endforeach; ?>

<!-- HTML or PHP code -->

I haven't updated the tareq1988/wp-eloquent because Eloquent is very slow. It takes a while to generate a query, let alone query the database. Also, Eloquent is used alongside of Laravel, which supports the latest PHP version all the time. But for WordPress plugins that's not the case. We have to support even PHP 5.6, which makes it a nightmare to keep up with the original package. That's why it didn't make sense to update the library.