Relationships

HasMany

A post owns many comments, which is a one-to-many link. The method name becomes the property you read, so fetching a post and its comments reads naturally.

The return type tells readers and tools what the method gives back. The related class is named, never spelled out with keys.

namespace App\Models; use Illuminate\Database\Eloquent\Model; use Illuminate\Database\Eloquent\Relations\HasMany; class Post extends Model { public function comments(): HasMany { return $this->hasMany(Comment::class); } }

BelongsTo

The other side of the link is a comment that belongs to one post. BelongsTo is the mirror image of HasMany, read from the child up to the parent.

namespace App\Models; use Illuminate\Database\Eloquent\Model; use Illuminate\Database\Eloquent\Relations\BelongsTo; class Comment extends Model { public function post(): BelongsTo { return $this->belongsTo(Post::class); } }

Eager loading

Reading comments inside a loop can fire one query per post, which slows pages down fast. The with method preloads the relation in a single extra query.

Eager load every relation the page prints. Lazy loading stays fine for single models outside loops.

$posts = Post::with("comments")->get(); foreach ($posts as $post) { echo count($post->comments); }

Save related

New children can be created through the relation itself. Laravel fills the foreign key from the parent, so you never set it by hand.

$post = Post::find(1); $post->comments()->create(["body" => "Nice post!"]);

Next: Query builder

Article author: Arthur Isaev