Nullable Object Must Have a Value ASP.NET MVC 5 Checkbox For

Question

Hi I have a CheckBox For

@Html.CheckBoxFor(model => model.VisitRequested.Value, new {onClick = "showHide();"})

It throws the exception (above) if the checkbox isn't clicked. I would like the value to be 0 or false if the check box remains unchecked.

The model code is:

[DisplayName("Request a Visit")]
public Nullable<bool> VisitRequested { get; set; }

possible duplicate of [MVC3: Creating checkbox for nullable boolean](http://stackoverflow.com/questions/6849774/mvc3-creating-checkbox-for-nullable-boolean) — hazzik, Mar 05 '14 at 20:51

Henk Mollema · Answer 1 · 2015-11-05T13:23:04.220

3

The Value property of a Nullable<T> throws an InvalidOperationException when the value is null (actually when HasValue == false). Try:

@Html.CheckBoxFor(model => model.VisitRequested, new {onClick = "showHide();"})

Just use model.VisitRequested and eventually wrap it inside an if:

@if (Model.VisitRequested.HasValue)
{
   @Html.CheckBoxFor(model => model.VisitRequested, new {onClick = "showHide();"}) 
}

edited Nov 05 '15 at 13:23

answered Mar 05 '14 at 18:51

Henk Mollema

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System.Nullable does not contain definition for GetValueOfDefault – ASPCoder1450 Mar 05 '14 at 18:54
An exception of type 'System.InvalidOperationException' occurred in System.Web.Mvc.dll but was not handled in user code Additional information: Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions. – ASPCoder1450 Mar 05 '14 at 18:58
I've used GetValueOrDefault(false) – ASPCoder1450 Mar 05 '14 at 18:58
Can you show the complete line of code you have in your view? – Henk Mollema Mar 05 '14 at 18:59
@Html.CheckBoxFor(model => model.VisitRequested.GetValueOrDefault(false), new { onClick = "showHide();" }) – ASPCoder1450 Mar 05 '14 at 19:00
That looks fine. Seems like your exception has nothing to do with this line of code. – Henk Mollema Mar 05 '14 at 19:02
Does this exception occurs at the same line of code? You might want to ask a new question if it's not. – Henk Mollema Mar 05 '14 at 19:05
Yes its at the exact same line – ASPCoder1450 Mar 05 '14 at 19:06
Ah I understand. What if you just use `model => model.VisitRequested`, without the `GetValueOrDefault()`. – Henk Mollema Mar 05 '14 at 19:38

evanmcdonnal · Answer 2 · 2014-03-05T20:46:25.940

0

Yes that's because model.HasValue is false. Add;

 if (model.VisitRequested.HasValue)
    @Html.CheckBoxFor(model => model.VisitRequested.Value, new {onClick = "showHide();"});
 else
    //somethings wrong, not sure what you want to do

Basically that is indicating that the object is null. In the docs you'll find;

Exception:
InvalidOperationException Condition:
The HasValue property is false

which is what you're encountering.

edited Mar 05 '14 at 20:46

answered Mar 05 '14 at 17:53

evanmcdonnal

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model does not exist in the current context. Do I have to use @{} symbols for the code? – ASPCoder1450 Mar 05 '14 at 18:09
@ASPCoder1450 I don't think so, I would guess there's some other little syntax error that's causing it. Oh, yeah I just saw it. I'll edit. I was accessing `HasValue` from `model` when there is one more layer of indirection. The error message isn't intuitive :| – evanmcdonnal Mar 05 '14 at 20:46

Nullable Object Must Have a Value ASP.NET MVC 5 Checkbox For

2 Answers2