The ViewData item that has the key 'SelectedItem' is of type 'System.String' but must be of type 'IEnumerable

Question

I have a dropdown list that is populating correctly on the page load but when I select a choice and submit it back with data from additional fields I am getting this error. Do I need to reset it back to the default value? In the below code "Industries" is a List of type SelectListItem.

@using (Html.BeginForm())
{
    @Html.DropDownListFor(n => n.SelectedItem, Model.Industries)
     <br>
      //MORE CONTROLS 
     <br>
     <input type="submit" value="Calculate" />
 }

[HttpGet]
public ActionResult Calculate()
{
    ClassName DataStuff = new ClassName ();
    return View(new ClassName { Industries = DataStuff.IndustryList() 
});
}

[HttpPost]
public ActionResult Calculate(ClassName  Items)
{
 ClassName CompleteItems = RetrieveData(Items);  
      // above additional calculations 
        return View(CompleteItems);
}

The model (with the relevant fields) is:

public class ClassName
{

    public string SelectedItem { get; set; }
    public IEnumerable<SelectListItem> Industries { get; set; }
    public List<SelectListItem> IndustryList()
    {
       //populating the DDL
    }
}

What is the type of Industries. it should be of type IEnumerable — user9405863, Apr 10 '18 at 14:48
It is of type List. Is that not correct for this circumstance? — Borges, Apr 10 '18 at 14:51
Try renaming public string SelectedItem { get; set; } to public string MySelectedItem { get; set; } — Felix Cen, Apr 10 '18 at 15:15
How would changing the name of the variable change the functionality? — Borges, Apr 10 '18 at 15:40

user9405863 · Accepted Answer · 2018-04-10T16:57:53.217

-1

1. Define Industries as IEnumerable<SelectListItem> or

if you defined Industries as List<SelectListItem> cast Industries to IEnumerable like

(IEnumerable<SelectListItem>)Model.Industries

2.In your model ,in place of public string SelectedItem { get; set; } use

public string Industry{ get; set; } and

in view update with new property use @Html.DropDownListFor(n => n.Industry, Model.Industries)

edited Apr 10 '18 at 16:57

answered Apr 10 '18 at 14:52

user9405863

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That produces the same error :( – Borges Apr 10 '18 at 14:58
Is your SelectListItem of type System.Web.Mvc.SelectListItem? check full name with namespace – user9405863 Apr 10 '18 at 15:05
Just checked. Yes it is. – Borges Apr 10 '18 at 15:07
try this public string Industry{ get; set; } – user9405863 Apr 10 '18 at 15:22
As opposed to a list? It has to hold the DDL contents doesn't it? – Borges Apr 10 '18 at 15:40
in place of public string SelectedItem { get; set; } use public string Industry{ get; set; } and in view use @Html.DropDownListFor(n => n.Industry, Model.Industries) – user9405863 Apr 10 '18 at 15:54
That works! In addition to the HTTPPOST method repopulating the DDL. It was null going back from the submit – Borges Apr 10 '18 at 16:05
did you update with @Html.DropDownListFor(n => n.Industry, Model.Industries) ? – user9405863 Apr 10 '18 at 16:16
Yes! It's clearer that way. – Borges Apr 10 '18 at 16:20
whats the error you are getting now? – user9405863 Apr 10 '18 at 16:20
No it's working! I said earlier that it works. – Borges Apr 10 '18 at 16:21
I'm new here so not enough to do that I think. – Borges Apr 10 '18 at 16:42
This has nothing whatsoever to do with the question – Apr 10 '18 at 21:18
@StephenMuecke clarify why its able to fix user's problem and he accepted answer? – user9405863 Apr 10 '18 at 21:23
You answer is completely wrong - OP model was just fine (and OP even stated your answer was not working - you just pressured them to accept your answer). Read the duplicate to understand what the problems was. – Apr 10 '18 at 21:27
OP even identified their own problem -_In addition to the HTTPPOST method repopulating the DDL. It was null going back from the submit_ That is what the issue was - it had nothing to do with you answer – Apr 10 '18 at 21:30

The ViewData item that has the key 'SelectedItem' is of type 'System.String' but must be of type 'IEnumerable

1 Answers1