Question

I’ve a web using asp.net MVC 3 with razor.

In one view I’m having an odd error with the checkbox helper.

Here is the razor code:

@Html.CheckBox("rememberPassword", Model.RememberPassword, new { tabindex = "4", style = "width:15px" })

The property in the model (which I set to true in the Model constructor):

public bool RememberPassword { get; set; }

And the logged error:

2012-04-13 01:20:33.334 [13   ] Error - Reference: 0413-012033-334 - Global site error, page: /es/login
System.InvalidOperationException: The parameter conversion from type 'System.String' to type 'System.Boolean' failed. See the inner exception for more information. ---> System.FormatException: -1' is not a valid value for Boolean. ---> System.FormatException: String was not recognized as a valid Boolean.
   at System.Boolean.Parse(String value)
   at System.ComponentModel.BooleanConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value)
   --- End of inner exception stack trace ---
   at System.ComponentModel.BooleanConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value)
   at System.Web.Mvc.ValueProviderResult.ConvertSimpleType(CultureInfo culture, Object value, Type destinationType)
   --- End of inner exception stack trace ---
   at System.Web.Mvc.ValueProviderResult.ConvertSimpleType(CultureInfo culture, Object value, Type destinationType)
   at System.Web.Mvc.ValueProviderResult.UnwrapPossibleArrayType(CultureInfo culture, Object value, Type destinationType)
   at System.Web.Mvc.ValueProviderResult.ConvertTo(Type type, CultureInfo culture)
   at System.Web.Mvc.HtmlHelper.GetModelStateValue(String key, Type destinationType)
   at System.Web.Mvc.Html.InputExtensions.InputHelper(HtmlHelper htmlHelper, InputType inputType, ModelMetadata metadata, String name, Object value, Boolean useViewData, Boolean isChecked, Boolean setId, Boolean isExplicitValue, IDictionary`2 htmlAttributes)
   at System.Web.Mvc.Html.InputExtensions.CheckBoxHelper(HtmlHelper htmlHelper, ModelMetadata metadata, String name, Nullable`1 isChecked, IDictionary`2 htmlAttributes)
   at System.Web.Mvc.Html.InputExtensions.CheckBox(HtmlHelper htmlHelper, String name, Boolean isChecked, Object htmlAttributes)
   at ASP._Page_Views_Login_Index_cshtml.Execute() in d:\[...]\Views\Login\Index.cshtml:line 49
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.StartPage.RunPage()
   at System.Web.WebPages.StartPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
   at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19()
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
   at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<>c__DisplayClass1e.<InvokeActionResultWithFilters>b__1b()
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)

Why is this happening?

Note:

It keeps getting odder and odder. As magically as the error started appearing (in a productive site some day without any updates or releases) not it has stopped. It’s been three days without the error. However, I’d still like to know why was it.

Answer 1

It had nothing to do with the way of creating the checkbox. In some very odd scenarios (which I had forgotten at all), this forms may be submitted (from other sites) without this parameter. In this cases the bool field was trying to obtained from the string “-1”.

One way of resolving this issue (that I have discovered to be a good practice) is to avoid “not-nullable” fields in the Model.