Fetch Specific Related Attributes with withAggregate()

Use withAggregate() to pull a single column value from a relationship via a SQL subquery without eager loading full model instances.

When you need a single attribute from a related model, eager loading the entire relationship wastes memory. Laravel's withAggregate() runs a subselect query directly in SQL.

use App\Models\Post;

// Pulls user name directly as $post->user_name via SQL subquery
$posts = Post::withAggregate('user', 'name')->get();

• Creates virtual attributes named {relation}_{column} or your alias
• Runs in a single database subquery instead of N+1 queries
• Underlies withCount(), withSum(), and withAvg() helpers