php - Laravel - how to sum() field from relation

Question

I'm trying to optimize this code because it's causing Timeout problems.

It's getting all items from database and performing SUM() in PHP.

public function getInstalledCost()
{
  $items = $this->stockItems()
                              ->where('status', 'INSTALADO')
                              ->with(['shipment' => function($q){ $q->select('id', 'item_cost'); }])
                              ->select('id','shipment_id')
                              ->get();

  $cost = 0;
  foreach($items as $i){
    $cost += $i->shipment->item_cost;
  }

  return $cost;
}

So is there any way to get this data already SUM() from the database?

question from:https://stackoverflow.com/questions/65910618/laravel-how-to-sum-field-from-relation

Answer 1

Summing a collection in Laravel could be written shorter using the sum() method

$items->sum(function ($item) {
    return count($item['item_cost']);
});

Just as a hint for later.

To sum a field of a relation you could probably do sth. like

StockItem::whereHas('shipment', function ($q) use ($shipmentId) {
  $q->where('shipment_id', $shipmentId);
})->sum('shipments.item_price');

I assume you have properly set up relationships between stockItems and shipments and have a shipments relation on your StockItem model.