How to fix The model item passed into the dictionary is of type error?

Question

I am trying to run my first ASP.NET MVC application. I created a cotroller and view. Data is taken from Database. However, when project can run but when I try to navigate Customer page I get following error.

The model item passed into the dictionary is of type 'System.Collections.Generic.List`1[MvcApplication3.Models.Customer]', but this dictionary requires a model item of type 'MvcApplication3.Models.Customer'.

I am bit confused here, as error says it has requesting model type.

Stack trace is

Stack Trace:

[InvalidOperationException: The model item passed into the dictionary is of type 'System.Collections.Generic.List1[MvcApplication3.Models.Customer]', but this dictionary requires a model item of type 'MvcApplication3.Models.Customer'.]
System.Web.Mvc.ViewDataDictionary1.SetModel(Object value) +585211
System.Web.Mvc.ViewDataDictionary..ctor(ViewDataDictionary dictionary) +371 System.Web.Mvc.ViewPage1.SetViewData(ViewDataDictionary viewData) +48 System.Web.Mvc.WebFormView.RenderViewPage(ViewContext context, ViewPage page) +73
System.Web.Mvc.WebFormView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +38
System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +115
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +295 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
System.Web.Mvc.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17() +23 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func1 continuation) +242
System.Web.Mvc.<>c_DisplayClass1c.b_19() +21 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList1 filters, ActionResult actionResult) +177
System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +89 System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +102 System.Web.Mvc.Async.WrappedAsyncResult1.End() +57 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +43
System.Web.Mvc.<>c_DisplayClass1d.b_18(IAsyncResult asyncResult) +14
System.Web.Mvc.Async.<>c_DisplayClass4.b_3(IAsyncResult ar) +23 System.Web.Mvc.Async.WrappedAsyncResult1.End() +62
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +57 System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +23 System.Web.Mvc.Async.WrappedAsyncResult1.End() +62
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +47
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
System.Web.Mvc.<>c_DisplayClass8.b_3(IAsyncResult asyncResult) +25
System.Web.Mvc.Async.<>c_DisplayClass4.b_3(IAsyncResult ar) +23 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +47 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9514812 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

Here is my controller code.

namespace MvcApplication3.Controllers
{
    public class CustomerController : Controller
    {
        //
        // GET: /Customer/

        public ActionResult Index()
        {
            Models.NorthwindDataContext nwd = new Models.NorthwindDataContext();
            return View(nwd.Customers.ToList());
        }

    }
}

Here is the view

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MvcApplication3.Models.Customer>" %>

<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
    Index
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

<h2>Index</h2>

</asp:Content>

<asp:Content ID="Content3" ContentPlaceHolderID="FeaturedContent" runat="server">
</asp:Content>

<asp:Content ID="Content4" ContentPlaceHolderID="ScriptsSection" runat="server">
</asp:Content>

Can anybody give me a hint to fix it?

Answer 1

You're trying to pass a collection to a view that's designed for a single object.

change your view declaration to

Inherits="System.Web.Mvc.ViewPage<IEnumerable<MvcApplication3.Models.Customer>>

Answer 2

What exactly confuses you? In your aspx file you've defined the model as a customer, yet you pass a list instead to it.

Expected model:

System.Web.Mvc.ViewPage<MvcApplication3.Models.Customer>

Your data:

return View(nwd.Customers.ToList());

Obviously a mismatch.

Answer 3

In your related view (i.e. the .cshtml file) look for the @model declaration: the ActionResult needs to return the right instance of the model class, e.g. if you have defined

@model Customer

then your ActionResult needs to be of type Customer. You want to return a list, hence you need to define

@model IEnumerable<Customer>

in the view.