MVC Create page returning exception - asp.net-mvc

Question

I am having problems getting my create function to work right. I am trying to create an Order object, which has a SalesPerson and Customer object in it. My order model looks like
public class Order
{
public int ID { get; set; }
public SalesPerson SalesPerson { get; set; }
public bool PreviousWork { get; set; }
public OrderStatus Status { get; set; }
public Customer Customer { get; set; }
public List<OrderLineItem> LineItems { get; set; }
}
I then created a view model:
public class OrderViewModel
{
private sunburstdb db = new sunburstdb();
public Order originalOrder { get; set; }
public IList<SelectListItem> SalesPeopleList { get; set; }
public IList<SelectListItem> CustomersList { get; set; }
public IList<SelectListItem> OrderStatusList { get; set; }
public OrderViewModel(Order order)
{
originalOrder = order;
}
}
In my controller I have the following:
//
// GET: /Order/Create
public ActionResult Create()
{
Order order = new Order();
OrderViewModel viewModel = new OrderViewModel(order);
//IList<SelectListItem> result = new List<SelectListItem>();
viewModel.SalesPeopleList = new List<SelectListItem>();
foreach (SalesPerson person in db.SalesPeople)
{
var temp = new SelectListItem();
temp.Text = person.FullName;
temp.Value = person.ID.ToString();
viewModel.SalesPeopleList.Add(temp);
}
//viewModel.SalesPeopleList = new SelectList(result);
//result.Clear();
viewModel.CustomersList = new List<SelectListItem>();
foreach (Customer person in db.Customers)
{
var temp = new SelectListItem();
temp.Text = person.FullName;
temp.Value = person.ID.ToString();
viewModel.CustomersList.Add(temp);
}
//viewModel.CustomersList = new SelectList(result);
return View(viewModel);
}
//
// POST: /Order/Create
[HttpPost]
public ActionResult Create(Order order)
{
if (ModelState.IsValid)
{
db.Orders.Add(order);
db.SaveChanges();
return RedirectToAction("Index");
}
return View(order);
}
Finally my view is pretty standard with a couple of fields to populate the data in the order.
#using (Html.BeginForm()) {
#Html.ValidationSummary(true)
<fieldset>
<legend>Order</legend>
<div class="editor-label">
#Html.LabelFor(model => model.originalOrder.SalesPerson)
</div>
<div class="editor-field">
#Html.DropDownList("Order.SalesPerson", Model.SalesPeopleList)
</div>
<div class="editor-label">
#Html.LabelFor(model => model.originalOrder.Customer)
</div>
<div class="editor-field">
#Html.DropDownList("Order.Customer", Model.CustomersList);
</div>
<div class="editor-label">
#Html.LabelFor(model => model.originalOrder.PreviousWork)
</div>
<div class="editor-field">
#Html.EditorFor(model => model.originalOrder.PreviousWork)
#Html.ValidationMessageFor(model => model.originalOrder.PreviousWork)
</div>
<p>
<input type="submit" value="Create" />
</p>
</fieldset>
}
When I run this and try to create a new order I get the following: The model item passed into the dictionary is of type 'Models.Order', but this dictionary requires a model item of type 'Models.OrderViewModel'. I thought maybe I needed to change the parameter in the create method to public ActionResult Create(OrderViewModel order) however when I do this the error is: No parameterless constructor defined for this object. Can someone provide some help to an MVC Noob about what I am doing wrong?

Answer 1

in the action pass the viewmodel.
The error you get is because you created only a constructor with parameters, but MVC wnat also a parameterless contructor.
Aps.net 4 will create it automatically for you if you don't specify any constructor, but if you define one, then it don't take initiative creating one that maybe you don't want.
Look here. That should explain better than me

Answer 2

So that happens during model binding as for me.
What is the best way to debug such circumstances is to implement model binder which is inherited from default one and set it as default model binder for your object (Order).
Try to provide more information for more specific answer.
You can use the link below as a sample of custom model binder and registration
http://www.markeverard.com/blog/2011/07/18/creating-a-custom-modelbinder-allowing-validation-of-injected-composite-models/
PS: in my opinion it's not the best way to put models into viewmodels.
but there still are implementations that contain commands and services so it's up to you.