Piye cara nemtokake Eloquent relationships?

Question

Accepted Answer

**Eloquent relationships** nandel carane tabel database ana gandhengane, ditemtokake minangka metode ing model. Laravel nyengkuyung kabeh jinis relationship sing umum — one-to-many, many-to-many, one-to-one, lan liyane — ngasikake akses object-oriented sing elegan menyang data sing ana gandhengane.

## One-to-many (hasMany / belongsTo)

```php
class User extends Model {
    public function posts() {              // a user HAS MANY posts
        return $this->hasMany(Post::class);
    }
}
class Post extends Model {
    public function author() {              // a post BELONGS TO a user (inverse)
        return $this->belongsTo(User::class);
    }
}

// access related data as properties (lazy-loaded)
$user->posts;          // a Collection of the user's Posts
$post->author;          // the Post's User
$user->posts()->where('published', true)->get();   // query the relationship
```

Relationship sing paling umum: parent `hasMany` anak-anake, lan saben anak `belongsTo` ing parent. Akses relationship minangka property bali menyang model(s) sing ana gandhengane.

## Many-to-many (belongsToMany)

```php
class Post extends Model {
    public function tags() {                // posts and tags — many-to-many
        return $this->belongsToMany(Tag::class);   // uses a pivot table (post_tag)
    }
}
$post->tags;                    // the post's tags
$post->tags()->attach($tagId);   // add an association
$post->tags()->detach($tagId);   // remove
$post->tags()->sync([1, 2, 3]);  // set exactly these
```

**Many-to-many** nggunakake pivot table (dikelola otomatis), nganggo `attach`/`detach`/`sync` kanggo ngelola asosiasi.

## Jinis relationship liya-liyane

```php
$this->hasOne(Profile::class);          // one-to-one
$this->hasManyThrough(...);              // has-many through an intermediate model
$this->morphMany(Comment::class, 'commentable');   // POLYMORPHIC (comments on posts OR videos)
```

## Eager loading (cegah N+1!)

```php
// ❌ N+1: a query per post to get each author
$posts = Post::all();
foreach ($posts as $post) { echo $post->author->name; }

// ✅ eager load with with() — fetches authors in ONE extra query
$posts = Post::with('author')->get();
```

Gunakake `with()` kanggo **eager-load** relationships lan cegah masalah N+1 query.

## Apa pentinge

Eloquent relationships iku penting banget kanggo bisa karo relational data ing Laravel — nyawisane saben aplikasi nduweni entitas sing ana gandhengane (users lan posts, posts lan tags, orders lan items), dadi paham carane nemtokake lan nggunakake relationships iku pengetahuan dasar sing kudu dimangerteni saben hari.

Ngerti jinis-jinis relationship lan kapan kudu nggunakake saben-sabenane — **`hasMany`/`belongsTo`** kanggo one-to-many (paling umum), **`belongsToMany`** kanggo many-to-many (karo pivot table lan `attach`/`detach`/`sync`), `hasOne` kanggo one-to-one, lan polymorphic relations kanggo asosiasi sing fleksibel — iku kudu dingerteni kanggo bisa nandel data sing rumit lan minangka salah sawijining fitur Eloquent sing paling kuat lan elegan.

Relationships ngasikake akses object-oriented sing intuisibel menyang data sing ana gandhengane (`$user->posts`, `$post->author`) tanpa kudu nulis joins manual, iki minangka kauntungan produktivitas sing gedhe.

Kritis banget, paham **eager loading karo `with()`** kanggo cegah **masalah N+1 query** (ngendi akses relationships ing loop nyebabake query saben rekord — iki isu performa sing akeh banget) iku kudu dingerteni, amarga relationships gampang banget nyebabake masalah N+1.

Dominating Eloquent relationships — nemtokake, akses related data, lan eager-loading kanggo cegah N+1 — iku pengetahuan inti sing asring digunakake sing dadi fondasi kanggo data modeling lan performa sing efektif ing aplikasi Laravel.