UNIT3D-Community-Edition/app/Models/Subscription.php

<?php
/**
 * NOTICE OF LICENSE.
 *
 * UNIT3D Community Edition is open-sourced software licensed under the GNU Affero General Public License v3.0
 * The details is bundled with this project in the file LICENSE.txt.
 *
 * @project    UNIT3D Community Edition
 *
 * @author     HDVinnie <hdinnovations@protonmail.com>
 * @license    https://www.gnu.org/licenses/agpl-3.0.en.html/ GNU Affero General Public License v3.0
 */

namespace App\Models;

use App\Traits\Auditable;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Subscription extends Model
{
    use HasFactory;
    use Auditable;

    /**
     * Belongs To A User.
     */
    public function user(): \Illuminate\Database\Eloquent\Relations\BelongsTo
    {
        return $this->belongsTo(User::class)->withDefault([
            'username' => 'System',
            'id'       => '1',
        ]);
    }

    /**
     * Belongs To A Topic.
     */
    public function topic(): \Illuminate\Database\Eloquent\Relations\BelongsTo
    {
        return $this->belongsTo(Topic::class);
    }

    /**
     * Belongs To A Forum.
     */
    public function forum(): \Illuminate\Database\Eloquent\Relations\BelongsTo
    {
        return $this->belongsTo(Forum::class);
    }

    /**
     * Only include subscriptions of a forum
     */
    public function scopeOfForum($query, $forum_id): Builder
    {
        return $query->where('forum_id', '=', $forum_id);
    }

    /**
     * Only include subscriptions of a topic
     */
    public function scopeOfTopic($query, $topic_id): Builder
    {
        return $query->where('topic_id', '=', $topic_id);
    }
}