Add order items

internal/repository/payment_order_item_repository.go

@@ -13,6 +13,7 @@ type PaymentOrderItemRepository interface {
 	Create(ctx context.Context, paymentOrderItem *entities.PaymentOrderItem) error
 	GetByID(ctx context.Context, id uuid.UUID) (*entities.PaymentOrderItem, error)
 	GetByPaymentID(ctx context.Context, paymentID uuid.UUID) ([]*entities.PaymentOrderItem, error)
+	GetPaidQuantitiesByOrderID(ctx context.Context, orderID uuid.UUID) (map[uuid.UUID]int, error)
 	Update(ctx context.Context, paymentOrderItem *entities.PaymentOrderItem) error
 	Delete(ctx context.Context, id uuid.UUID) error
 }
@@ -60,3 +61,34 @@ func (r *PaymentOrderItemRepositoryImpl) Update(ctx context.Context, paymentOrde
 func (r *PaymentOrderItemRepositoryImpl) Delete(ctx context.Context, id uuid.UUID) error {
 	return r.db.WithContext(ctx).Delete(&entities.PaymentOrderItem{}, "id = ?", id).Error
 }
+
+// GetPaidQuantitiesByOrderID efficiently aggregates paid quantities for an order using SQL
+func (r *PaymentOrderItemRepositoryImpl) GetPaidQuantitiesByOrderID(ctx context.Context, orderID uuid.UUID) (map[uuid.UUID]int, error) {
+	type Result struct {
+		OrderItemID   uuid.UUID `json:"order_item_id"`
+		TotalQuantity int       `json:"total_quantity"`
+	}
+
+	var results []Result
+
+	// Efficient SQL query that aggregates quantities in the database
+	err := r.db.WithContext(ctx).
+		Table("payment_order_items poi").
+		Select("poi.order_item_id, SUM(poi.quantity) as total_quantity").
+		Joins("JOIN payments p ON poi.payment_id = p.id").
+		Where("p.order_id = ?", orderID).
+		Group("poi.order_item_id").
+		Scan(&results).Error
+
+	if err != nil {
+		return nil, err
+	}
+
+	// Convert results to map
+	paidQuantities := make(map[uuid.UUID]int)
+	for _, result := range results {
+		paidQuantities[result.OrderItemID] = result.TotalQuantity
+	}
+
+	return paidQuantities, nil
+}