MangaDex/app/Models/Manga.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Manga extends Model
{
    use HasFactory;

    protected $fillable = ['title', 'slug', 'summary', 'excerpt', 'cover', 'author_id'];

    public function user()
    {
        return $this->belongsTo(User::class, 'author_id');
    }

    public function chapters()
    {
        return $this->hasMany(Chapter::class);
    }

    //latest and oldest chapter
    // public function latestChap()
    // {
    //     return $this->chapters()->one()->latestOfMany();
    // }
    
    public function lastChap()
    {
        return $this->chapters()->one()->ofMany('chapter_no', 'max');
    }

    public function firstChap()
    {
        return $this->chapters()->one()->ofMany('chapter_no', 'min');
    }

    public function genres()
    {
        return $this->belongsToMany(Genre::class);
    }
}