asp.net mvc dropdownlistfor Object reference not set to an instance of an object error

Question

I am trying to create a drop down list using asp.net mvc.

Model:

    public string Status { get; set; }

    public List<SelectListItem> StatusList { get; set; }

    public AddUser()
    {
        StatusList = new List<SelectListItem>
                         {
                             new SelectListItem{Value = "0",Text = "0"},
                             new SelectListItem{Value = "1",Text = "1"}
                         };
    }

View:

<%: Html.DropDownListFor(m=>m.Status,new SelectList(Model.StatusList,"Value","Text")) %>
<%: Html.ValidationMessageFor(m => m.Status) %>

I don't know why but I keep getting this error:

Object reference not set to an instance of an object.

Anyone knows what I am doing wrong?

Are you sure you are instantiating StatusList by calling AddUser? Is the correct model being used in the view? Is the view being passed in by the controller? — Travis J, Mar 23 '12 at 23:45
Why in the world are you using `new SelectList(Model.StatusList,"Value","Text")` - `StatusList` is already `IEnumerable` - your just creating an identical `IEnumerable` from the first one - its just `Html.DropDownListFor(m => m.Status, Model.StatusList)` — , Jan 11 '17 at 12:00

score 1 · Accepted Answer · answered Mar 24 '12 at 01:19

This error usually happens when you leave a field of model null or the model is null

Make sure that "Status" isn't null and your return the model in "View" just like this:

    //end of an action code
    AddUser model = new AddUser();

    model.Status = "0"; //status can't be null (cause the the exception cited earlier)

    return View(model);  //if you do not pass the model as argument the model will be null in view
}

And one more tip for u:
The class SelectList implements IEnumerable<SelectListItem> so in view your code may look something like this:

<%: Html.DropDownListFor(m=>m.Status, Model.StatusList) %>
<%: Html.ValidationMessageFor(m => m.Status) %>

You don't need instantiate again.

Yeah, I didn't pass the model to the view. Was still to new to ASP.NET MVC. Such a simple mistake. Thanks for the help. — Houa Lee, Sep 14 '12 at 17:44

score 0 · Answer 2 · answered Mar 24 '12 at 00:09

0

I think Travis is right, you've forgot install StatusList, maybe it's null.

answered Mar 24 '12 at 00:09

Anton

1,583
12
17

How would you install StatusList? – Houa Lee Mar 24 '12 at 00:19

asp.net mvc dropdownlistfor Object reference not set to an instance of an object error

2 Answers2