Laravel eloquent order by sum of hasMany or by join

Question

I would like to order my products by the those who do have the most likes. I have one products table, one likes table and one users table.

This is how my likes table looks like: id, user_id, product_id, value

The value can either be 1 or -1 which is equal to one like or one dislike.

In my products model I have defined those relationships:

public function likes()
{
    return $this->belongsToMany('App\Models\User', 'products_likes', 'product_id', 'user_id')->withPivot('value')->withTimestamps();
}

public function productLikes()
{
    return $this->hasMany('App\Models\ProductLike');
}

However, now I would like to get the first 20 products which have the most sum of likes. This is how I tried to solve this, however, I cannot solve my problem...

$products = Product::select('products.*', DB::raw('SUM(products_likes.value) as sumLikes'))
            ->join('products_likes', 'products_likes.product_id', '=', 'products.id')
            ->orderBy('sumLikes', 'DESC')
            ->get();

However, this results in a weird group by sql problem:

QLSTATE[42000]: Syntax error or access violation: 1140 Mixing of GROUP columns (MIN(),MAX(),COUNT(),...) with no GROUP columns is illegal if there is no GROUP BY clause (SQL: select `products`.*, SUM(products_likes.value) as sumLikes from `products` inner join `products_likes` on `products_likes`.`product_id` = `products`.`id` order by `sumLikes` desc) 

Does anyone knows how I can archive this? I want to have my database to perform the ordering job and not Laravel. I have found some solutions here as well but they suggest to perform an all() and with("likes") query and use sortByDesc after the query got executed ( here ). But this brings down performance.

Kind regards

Answer 1

From laravel 5.2 onwards, you can use the withCount method to add a 'likes_count' subquery column, which can be customized like this:

Product::query()
    ->withCount(['likes as sumLikes' => function ($query) {
        return $query->select(\DB::raw('SUM(products_likes.value) AS sumLikes'));
    }])
    ->orderBy('sumLikes', 'DESC')
;

A similar result can be achieved on Laravel 5.1 or older versions by writing the subquery yourself:

$subquery = ProductLike::query()
    ->selectRaw('SUM(product_likes.value) as sumLikes')
    ->whereRaw('product_likes.product_id = products.id')
;
Product::query()
    ->addSelect(DB::raw($subquery->toSql()))
    ->orderBy('sumLikes', 'DESC')
;

Another way would be using joins, like you were attempting to, but you need to GROUP BY the products for it to work.

Product::query()
    ->addSelect(DB::raw('SUM(products_likes.value) as sumLikes'))
    ->join('products_likes', 'products_likes.product_id', '=', 'products.id')
    ->groupBy('products.id')
    ->orderBy('sumLikes', 'DESC')
;

You may need to specify the columns in your select, and group by each one of them, depending on your Database Engine.