在ManyToMany产品类别关系中通过急切加载仅获取X产品模型

Question

I have a ManyToMany relationship between Category and Product Model.

Product Model is like this :

class Product extends Model
    {
        protected $primaryKey = 'product_id';

        public function categories ()
        {
            return $this->belongsToMany('App\Category', 'category_product', 'product_id', 'cat_id');
        }
}

And Category Model is :

class Category extends Model
        {
            protected $primaryKey = 'cat_id';

            public function products (){
            return $this->belongsToMany('App\Product','category_product','cat_id','product_id');
        }
    }

Now , I want to fetch only last 4(for example) products of each Category. for that I write this :

$categories =   Category::with([
    'products'  =>  function($query){
        $query->select('products.product_id')->orderBy('created_at','desc')->take(4);
    }
])->get();

But this does not work properly and return unexpected products count?

How Can I do that?

Answer 1

If you want the last X number of products per category you can try something like :

Category::with(['products' => function($query) {
    $query->orderBy('updated_at','desc')->take(X);
}])->get();

This should return a Collection of Categories in which you should have no more than the desired number of products per category.

Hope it helps.