未设置ASP.NET MVC对象引用（向模型添加值）

Question

I have stupid problem with my model and controller. I am trying to show two models on one view with Partial Views.

When I fill model in controller I getting this message Object reference not set.. But I am not sure why?

Here is my controller and models:

Controller:

public ActionResult MultiView()
{

    ChartItem c = new ChartItem();
    c.Name = "Chart";

    ChartItem c1 = new ChartItem();
    c1.Name = "Chart1";

    List<ChartItem> a = new List<ChartItem>();
    a.Add(c);
    a.Add(c1);

    ListItem l = new ListItem();
    l.Name = "List";
    ListItem l1 = new ListItem();
    l1.Name = "List1";

    List<ListItem> b = new List<ListItem>();
    b.Add(l);
    b.Add(l1);

    MultiModel m = new MultiModel();
    m.ChartItems.Add(c);
    m.ListItems.AddRange(b);

   List<MultiModel> model = new List<MultiModel>();
    model.Add(m);



    return View(model);
}

Model:

namespace MVCPArtial.Models
{
    public class ChartItem
    {
        public string Name { get; set; }
    }
}

Model:

namespace MVCPArtial.Models
{
    public class ListItem
    {
        public string Name { get; set; }
    }
}

Model:

namespace MVCPArtial.Models
{
    public class MultiModel
    {
        public List<ChartItem> ChartItems { get; set; }
        public List<ListItem> ListItems { get; set; }
    }

}

Error:

Answer 1

You have not initialized the collections in MultiModel . Either add a default constructor

public class MultiModel
{
    // add parameterless constructor
    public MultiModel()
    {
        ChartItems = new List<ChartItem>();
        ListItems  = new List<ListItem>)();
    }
    public List<ChartItem> ChartItems { get; set; }
    public List<ListItem> ListItems { get; set; }
}

Or in the MultiView() method, initialize the collections

MultiModel m = new MultiModel();
m.ChartItems = new List<ChartItem>(); // add this
m.ListItems  = new List<ListItem>)(); // add this
m.ChartItems.Add(c);
m.ListItems.AddRange(b);