CODEWITHSUNDEEP
asp.net-mvc
Animesh D
Animesh D

Reputation: 5002

NullReferenceException: Object reference not set to an instance of an object

I have searched SO for similar posts and have not been successful with any given solutions. So I have posted this again.

I am trying to post some information back to the database in this Controller Action. This Action is called when Save button is clicked on the View.

    [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult EditDetail(int id, FormCollection fvals)
    {
        Environments env = environmentsRepository.GetEnvironmentDetail(id);
        UpdateModel(env);
        environmentsRepository.Save();
        return RedirectToAction("List", new RouteValueDictionary(new 
        {controller="Environments", action="List", id = 1}));  
    }

When I click on the Save button, I get the following error:

Line 32:
Line 33:
Line 34: <% foreach (var environment in Model) <--Error in this line
Line 35: { %>
Line 36: 

[NullReferenceException: Object reference not set to an instance of an object.]
   ASP.views_environments_list_aspx.__RenderContent2(HtmlTextWriter __w, Control     parameterContainer) in e:\code\ossp\WebUI\Views\Environments\List.aspx:34

Please let me know what I am missing? How do I resolve the error?

List View: http://pastebin.ubuntu.com/544767/
List Action: http://pastebin.ubuntu.com/544768/

Resolution:
I have realized that I was passing the wrong parameter 'id' instead of 'page', to the List view.

Thanks everyone for their pointers. I was able to learn a lot due to this discussion. Unfortunately, I am still at 11 to be able to give some votes. Thanks!

Upvotes: 0

Views: 2378

Answers (2)

ozz
ozz

Reputation: 5366

"Page" does not have a value, so as Ahmad pointed out it looks like you are returning back an empty View as per the ELSE

if (page.HasValue)
    return View(environmentsRepository.Environments.Skip(((int)page - 1) * PageSize).Take(PageSize).ToList());
else
    return View(); ///TODO Handle This

Have you tried debugging through to see what flow the code takes?

Upvotes: 1

Darin Dimitrov
Darin Dimitrov

Reputation: 1038790

The problem is that inside your EditDetail at the end you are redirecting to the List action of the Environments controller and I suppose that this action renders a strongly typed view. The problem is that the model you passed to the view was null. So your controller action might look something like this:

public ActionResult List(int id)
{
    var model = FetchModelFromSomewhere(id); // this probably returns null here
    return View(model);
}

And inside your view you are trying to enumerate over the model which is null:

<% foreach (var environment in Model) { %>

and you are getting the exception. So make sure that the model you are passing to the List view is not null.

Upvotes: 2

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