php - Sum relationship column before pagination in Laravel

I have a table that has products with price and a second table that has discounts with amount column. What I am looking for is a total of all products prices and all discounts amount from the query.The discount relation is a belongsTo

I am using the following to get my total product prices before my pagination.

$query->with(['discount']);

$total_cost = $query->sum('price');

$products = $query->paginate(25);

It works great for getting the $total_cost but I can't figure out how to get discounts and sum the amount column.

Solution:

Concept of eager loading with relationship will help with that.

$query->with(['discount' => function($another_query) {
    $another_query->// do your sum here
} ]);