public void AddEditWarehouse(WarehouseDTO warehouse, string username, int id = 0)
        {
            if (id == 0)
            {
                // ADD
                Warehouse newWarehouse = new Warehouse {
                    Name    = warehouse.Name,
                    AdminId = _warehouseRepo.FindUserByUsername(username).Id,
                };

                _warehouseRepo.Add(newWarehouse);
                _warehouseRepo.SaveChanges();
            }
            else
            {
                // EDIT
            }
        }