Ekapp/skolehjem/app/ResourceExtension.php

<?php

//The Model to a certain Controller, should contain a class with Controller name to which it belongs.
// Allows needed strings to passed onto the database. if there is none. class should appear empty.

//Reference to where the file belongs.
namespace App;

//allows the use of Model library
use Illuminate\Database\Eloquent\Model;

//Class of which should extend Model Library
class ResourceExtension extends Model
{
    protected $fillable = [
        'extension', 'description', 'resource_category_id'
    ];

    public function resources() {
        return $this->hasMany("App\Resource");
    }
}