Apa itu Polymorphic?

Polymorphic memungkinkan satu model berelasi dengan berbagai model berbeda menggunakan satu set kolom.

Contoh: Comment bisa dimiliki oleh Post maupun Video.

posts       videos      comments
id          id          id
title       title       body
                        commentable_id    ← ID dari post/video
                        commentable_type  ← Nama class: App\Models\Post

Migrasi

Schema::create('comments', function (Blueprint $table) {
    $table->id();
    $table->text('body');
    $table->unsignedBigInteger('commentable_id');
    $table->string('commentable_type');
    $table->timestamps();

    // Buat index untuk performa
    $table->index(['commentable_id', 'commentable_type']);
});

Definisi Relasi

Model Comment:

class Comment extends Model
{
    public function commentable(): \Illuminate\Database\Eloquent\Relations\MorphTo
    {
        return $this->morphTo();
    }
}

Model Post:

class Post extends Model
{
    public function comments(): \Illuminate\Database\Eloquent\Relations\MorphMany
    {
        return $this->morphMany(Comment::class, 'commentable');
    }
}

Model Video:

class Video extends Model
{
    public function comments(): \Illuminate\Database\Eloquent\Relations\MorphMany
    {
        return $this->morphMany(Comment::class, 'commentable');
    }
}

Penggunaan

// Tambah comment ke post
$post = Post::find(1);
$post->comments()->create(['body' => 'Artikel yang bagus!']);

// Tambah comment ke video
$video = Video::find(1);
$video->comments()->create(['body' => 'Video informatif!']);

// Ambil semua comment dari post
$comments = $post->comments;

// Akses parent dari comment (bisa Post atau Video)
$comment = Comment::find(1);
$parent  = $comment->commentable; // Mengembalikan Post atau Video
echo get_class($parent); // App\Models\Post

Many-to-Many Polymorphic: morphToMany

Contoh: Tag bisa menempel di Post dan Video sekaligus.

taggables (pivot)
  tag_id
  taggable_id
  taggable_type
class Tag extends Model
{
    public function posts(): MorphToMany
    {
        return $this->morphedByMany(Post::class, 'taggable');
    }

    public function videos(): MorphToMany
    {
        return $this->morphedByMany(Video::class, 'taggable');
    }
}

class Post extends Model
{
    public function tags(): MorphToMany
    {
        return $this->morphToMany(Tag::class, 'taggable');
    }
}

Ringkasan Episode 5