Nullable object must have a value While rendering a CheckBox in Razor

Question

I am trying to create a CheckBox in MVC using Razor and here is the Below code for it :

@Html.CheckBoxFor(m => m.PDModel.EducationMasterList[0].eduMarksheet, new { @class = "marksheet" })

But it is showing error Cannot implicitly convert 'bool?' to 'bool'. Are you missing the type cast. To Solve this i have used @Html.CheckBoxFor(m => m.PDModel.EducationMasterList[0].eduMarksheet.Value, new { @class = "marksheet" }) and it is giving this error : Nullable object must have a value.

and @Html.CheckBoxFor(m => m.PDModel.EducationMasterList[0].eduMarksheet.GetValueOrDefault(), new { @class = "marksheet" }) and it is giving this error : Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions.

Any Suggestion will be thankful.

Thanks in Adavance

You should change your field to bool. There is no sense to have chechbox value which can be null. — mybirthname
– mybirthname, Commented Oct 25, 2014 at 8:37

user3559349 · Accepted Answer · 2014-10-25 08:15:27Z

1

You cannot create a checkbox for a nullable bool. A check box has 2 states, checked/true and unchecked/false, but a nullable bool has 3 states, true, false and null so its not possible to post back a value indicating if its false or null.

You can use

@Html.EditorFor(m => m.PDModel.EducationMasterList[0].eduMarksheet, ...

which will render a dropdown list containing 3 values ("True", "False" and "Not set"). Another option is to create 3 radio buttons.

Note that @Html.CheckBoxFor(m => m.PDModel.EducationMasterList[0].eduMarksheet.Value, ..) would be pointless since it creates a checkbox and associated hidden input with the attribute name="EducationMasterList[0].eduMarksheet.Value" so when it posted back it would not match any model property and binding would fail.

answered Oct 25, 2014 at 8:15

user3559349

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5 Comments

user3559349 Over a year ago

Only if you make your property bool, not bool?

Naveen Over a year ago

I can't make that feild bool? to bool because if user has not checked it , it should enter null value in that feild. Thats why i have made that feild Nullable

user3559349 Over a year ago

In that case you need @Html.EditorFor() or 3 radio buttons (for "true, "false" and "not set") as I indicated in my answer. But if the user has not checked it why cant that mean "false" instead of "null". A nullable bool is only required when you need 3 possible values for example - YES or NO or I DONT KNOW

user3559349 Over a year ago

Then change the property to bool. You cant do the impossible.

user3559349 Over a year ago

Then perhaps you should consider accepting the answer to close this out

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