Model relationships in ASP.NET MVC

I recently started evaluating ASP.NET MVC. While it is really easy and quick to create Controllers and Views for Models with only primitive properties (like shown in the start开发者_开发技巧er videos from the official page) I didn't find any good way to work with references to complex types. Let's say, I have these Models:

public class Customer {  
    public int Id { get; set; }  
    public string Name { get; set; }  
    public Address Address { get; set; }  
    public IList<Order> Orders { get; set; }  
}

public class Address {  
    public int Id { get; set; }  
    public string .....  
    .....  
}

public class Order {  
    public int Id { get; set; }  
    public Customer Customer { get; set; }  
    public string OrderName { get; set; }  
    .....  
}

Note that I don't have foreign keys in the models (like it's typical for LINQ to SQL, which is also used in the sample video) but an object reference.

How can I handle such references in asp.net mvc? Does someone has some good tips or links to tutorials about this problem? maybe including autobinding with complex types.

---

You can use Data Transfer Objects for this issue or you can use expand methods on entity - include method in EF -

Nothing is different with primitive properties. If thats not what you mean, correct me then I'll help you again

Thanks

DTO:

public class OrderDTO
{
    public int Id { get; set; }
    public int CustomerId { get; set; }
    public string CustomerName { get; set; }
}

NHibernate repository:

public IList<OrderDTO> GetOrders()
{
    return Session.Linq<Order>()
                    .Select(o => new OrderDTO {
                                        Id = o.Id
                                        CustomerId = o.Customer.Id
                                        CustomerName = o.Customer.Name
                                        ...
                    }).ToList();
}

View:

With Expand - Include - Model type is 'Order':

<%= Model.Customer.Name %>

With DTO - Model type is 'OrderDTO':

<%= Model.CustomerName %>

edit:

Okay, first you may want to use FormViewModel for create/edit actions. like this;

Controller:

public ActionResult Edit(int id)
{
    Order order = null; // OrderService.Get(id);
    IList<Customer> customers = null; // CustomerService.GetAll();

    OrderFormViewModel model = OrderFormViewModel.Create(order);
    model.Customers = customers.Select(c => new SelectListItem {
        Value = c.Id,
        Text = c.Name
    });

    return View(model);
}

[HttpPost]
public ActionResult Edit(int customerId, Order order)
{
    //customerId - selected from dropdown.
}

public class OrderFormViewModel
{
    public static OrderFormViewModel Create(Order order)
    {
        return new OrderFormViewModel {
            Order = order
        };
    }

    public Order Order { get; internal set; }
    public IEnumerable<SelectListItem> Customers { get; internal set; }
    public int CustomerId { get; internal set; }
}

View:

<%= Html.DropDownListFor(o => o.CustomerId, Model.Customers) %>

---

I would combine everything into my view model:

CustomerViewModel.Customer
CustomerViewModel.Address
CustomerViewModel.Orders // maybe an IEnumerable<Order>
CustomerViewMode.CurrentOrder

You should be able to bind your complex objects without too much trouble using some of the input helpers:

//.. begin form
<%=Html.HiddenFor(m=>m.Customer.Id)%>
<%=Html.TextboxFor(m=>m.Customer.FirstName)%>
<%=Html.TextBoxFor(m=>m.Address.City)%>
<%=Html.TextBoxFor(m=>m.ActiveOrder.OrderName%>
//.. submit ..
//.. end form ..

The should bind back ok if your action method looks like:

[HttpPost]
public ActionResult UpdateComplexObject(string id, CustomerViewModel customerViewModel) {
// if (!id.Equals(customerViewModel.Customer.Id) throw something
// just one of my own conventions to ensure that I am working on the correct active
// entity - string id is bound from the route rules.
ValidateModel(customerViewModel);
service.UpdateCustomer(customerViewModel.Customer);
serviceOrder.UpdateOrder(customerViewModel.ActiveOrder);
serviceAddress.UpdateAddress(customerViewModel.Address);
return RedirectToAction("DisplayComplexObject"); // or whatever
}

Hal

---

I prefer to keep my views as 'dumb' as possible, so I like to create custom view models for binding.

In your controller you can map your rich domain objects to the view model's flatter model. For example:

public class ChooseCustomerModel {

    public Order Order { get; set; }

    // Project Customer objects into this container, which is easy to bind to
    public IDictionary<int, string> PotentialCustomers { get; set; }
}

If you're looking for good material on this subject, I recommend ASP.NET MVC View Model Patterns.