private void CreateOrUpdateCart(int employeeId, int productId, int quantity, CartUpdateMode mode)
{
using (var context = new eToolsContext())
{
// collect entities
Employee employee = context.Employees.Find(employeeId);
StockItem product = context.StockItems.Find(productId);
// validate request
List <string> errors = ValidateCartItem(employee, product, quantity);
if (errors.Count > 0)
{
string errorMessage = (mode == CartUpdateMode.INCREMENTAL) ?
"Product not added to cart." :
"Product not updated in cart.";
throw new BusinessRuleException(errorMessage, errors);
}
else
{
// validation passed, update cart
CreateOrUpdateCartValidated(employee, product, quantity, mode);
}
}
}
// Update cart and cartitems. Must be called with validated parameters.
private void CreateOrUpdateCartValidated(Employee employee, StockItem product, int quantity, CartUpdateMode mode)
{
// handle cart update in one transaction
using (var context = new eToolsContext())
{
// find shopping cart
ShoppingCart cart = context.ShoppingCarts.Where(x => x.EmployeeID == employee.EmployeeID).FirstOrDefault();
// create new cart if not found or update existing cart
if (cart == null)
{
// create new cart
cart = new ShoppingCart();
cart.EmployeeID = employee.EmployeeID;
cart.CreatedOn = DateTime.Now;
context.ShoppingCarts.Add(cart);
}
else
{
// update existing cart
cart.UpdatedOn = DateTime.Now;
context.Entry(cart).Property(x => x.UpdatedOn).IsModified = true;
// context.Entry(cart).State = System.Data.Entity.EntityState.Modified;
}
// find cart item in cart
ShoppingCartItem item = cart.ShoppingCartItems.Where(x => x.StockItemID == product.StockItemID).FirstOrDefault();
// add item to cart if not found or update qty if found
if (item == null)
{
// add item to cart
item = new ShoppingCartItem();
item.ShoppingCartID = cart.ShoppingCartID;
item.StockItemID = product.StockItemID;
item.Quantity = quantity;
context.ShoppingCartItems.Add(item);
}
else
{
// update existing item in cart
if (mode == CartUpdateMode.INCREMENTAL)
{
item.Quantity += quantity;
if (item.Quantity > product.QuantityOnHand)
{
throw new BusinessRuleException(
"Product not added to cart.",
string.Format("Not enough stock: requested {0} available {1}.",
item.Quantity,
product.QuantityOnHand));
}
}
else
{
item.Quantity = quantity;
if (item.Quantity > product.QuantityOnHand)
{
throw new BusinessRuleException(
"Product not added to cart.",
string.Format("Not enough stock: requested {0} available {1}.",
item.Quantity,
product.QuantityOnHand));
}
}
context.Entry(item).Property(x => x.Quantity).IsModified = true;
}
// commit transaction
context.SaveChanges();
}
}
