Model binding doesn't work for me - MVC 3

Question

First of all i'm quite new to the MVC 3 method, so please don't be to hard on me. I try to use model binding, with a model that has a List of another model. Attributes of this model succesfully bind, but the list doesn't.

Here are the classes:

public class Company
{
    public int Id { get; set; }
    public String Name { get; set; }
    public List<Address> Addresses { get; set; }
}

public class Address
{
    public int Id { get; set; }
    public String Street { get; set; }
}

This is my model:

public class CompanyDetailsModel
{
    public Classes.Company Company { get; set; }
    public List<Address> Addressess { get; set; }
}

My controller (GET)

    public ActionResult Create()
    {
        var model = new CompanyDetailsModel();
            model.Addressess = new List<Address>();

        //Just for this example like this
            model.Addressess.Add(new Address());
            model.Addressess.Add(new Address());
        return View(model);
    }

My controller (POST)

    [HttpPost]
    public ActionResult Create(CompanyDetailsModel CompanyDetailsModel)
    {
        foreach (var address in CompanyDetailsModel.Addressess)
        {
         //logic
        }

        return View();
    }

View:

(also imported model of course)
in inside the form:

   foreach (var address in Model.Addressess)
   {
   <fieldset>
   <legend>Test</legend>
   @Html.EditorFor(model => address.Street)
   </fieldset>
   }

Error : [NullReferenceException: Object reference not set to an instance of an object.]

Extra info: I can save all the attributes of company without any problems using the same CompanyDetailsModel.

I hope someone can help me out/point me in the right direction.

Thanks in advance

Gyo

Stack trace

Line 45:         public ActionResult Create(CompanyDetailsModel CompanyDetailsModel)
Line 46:         {
Line 47:             foreach (var address in CompanyDetailsModel.Addressess)
Line 48:             {
Line 49:   

Source File: C:\Users\Goz\Documents\Visual Studio 2010\Projects\Portaal\Controllers\CompaniesController.cs Line: 47

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
   Portaal.Controllers.CompaniesController.Create(CompanyDetailsModel CompanyDetailsModel) in C:\Users\Goz\Documents\Visual Studio 2010\Projects\Portaal\Controllers\CompaniesController.cs:47
   lambda_method(Closure , ControllerBase , Object[] ) +108
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +17
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +208
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
   System.Web.Mvc.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12() +55
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +263
   System.Web.Mvc.<>c__DisplayClass17.<InvokeActionMethodWithFilters>b__14() +19
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +191
   System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +343
   System.Web.Mvc.Controller.ExecuteCore() +116
   System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +97
   System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10
   System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +37
   System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21
   System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +12
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62
   System.Web.Mvc.<>c__DisplayClasse.<EndProcessRequest>b__d() +50
   System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action f) +7
   System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +60
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8920029
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184

Answer 1

The reason why you get NullReferenceException is incorrect list binding. Mvc has a few patterns in order to appropriate Collection binding. http://haacked.com/archive/2008/10/23/model-binding-to-a-list.aspx here is good explanation of collection binding in MVC.

Answer 2

@Html.EditorFor(model => address.Street)

In creation of Model you have not specified Street value for address objects.

If this is not the case then please let us know the stack trace for the exception.