Why is EditorFor in my ASP.NET MVC 2 application throwing ArgumentNullException?

Question

I have a weird problem with EditorFor in one of my views. The following code throws an ArgumentNullException.

<%: Html.EditorFor(x => x.Name) %>

However, the following code is fine.

<%: Html.TextBoxFor(x => x.Name) %>

Model.Name is a string variable - and it's set.

EditorFor works in another view - until this view crashes, at which point then I have to restart the development web server (Cassini) or all the EditorFor calls crash with the same message.

I ran a test with the MVC 2 source, hoping I could get some insight, but that worked OK! Presumably the MVC 2 RTM source on there should be the one in VS2010 (dates seem to tie in).

I've just switched to TextBoxFor, as that's fine - but I'd like to know what the issue is. I'm running under .NET 4, VS2010 and Win7 x64.

[Update: same issue occurs with DisplayFor.]

Partial stack trace is:

[ArgumentNullException: Value cannot be null.
Parameter name: stream]
   System.IO.StreamReader..ctor(Stream stream, Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize) +9496369
   System.Web.UI.TemplateParser.ParseFile(String physicalPath, VirtualPath virtualPath) +232
   System.Web.UI.TemplateParser.ParseInternal() +86
   System.Web.UI.TemplateParser.Parse() +160
   System.Web.Compilation.BaseTemplateBuildProvider.get_CodeCompilerType() +110
   System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) +65
   System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() +218
   System.Web.Compilation.BuildProvidersCompiler.PerformBuild() +40
   System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) +8945798
   System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +320
   System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +111
   System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound) +125
   System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp) +52
   System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(String virtualPath, Type requiredBaseType) +28
   System.Web.Mvc.BuildManagerWrapper.System.Web.Mvc.IBuildManager.CreateInstanceFromVirtualPath(String virtualPath, Type requiredBaseType) +36
   System.Web.Mvc.WebFormView.Render(ViewContext viewContext, TextWriter writer) +172
   System.Web.Mvc.Html.TemplateHelpers.ExecuteTemplate(HtmlHelper html, ViewDataDictionary viewData, String templateName, DataBoundControlMode mode, GetViewNamesDelegate getViewNames) +1154
   System.Web.Mvc.Html.TemplateHelpers.TemplateHelper(HtmlHelper html, ModelMetadata metadata, String htmlFieldName, String templateName, DataBoundControlMode mode, Object additionalViewData, ExecuteTemplateDelegate executeTemplate) +1626
   System.Web.Mvc.Html.TemplateHelpers.TemplateHelper(HtmlHelper html, ModelMetadata metadata, String htmlFieldName, String templateName, DataBoundControlMode mode, Object additionalViewData) +86
   System.Web.Mvc.Html.TemplateHelpers.TemplateFor(HtmlHelper`1 html, Expression`1 expression, String templateName, String htmlFieldName, DataBoundControlMode mode, Object additionalViewData, TemplateHelperDelegate templateHelper) +210
   System.Web.Mvc.Html.TemplateHelpers.TemplateFor(HtmlHelper`1 html, Expression`1 expression, String templateName, String htmlFieldName, DataBoundControlMode mode, Object additionalViewData) +129
   System.Web.Mvc.Html.EditorExtensions.EditorFor(HtmlHelper`1 html, Expression`1 expression) +87

Answer 1

What does the Editor template look like for the property you are passing? (I assume x.Name is a string, so you should have a template called String.ascx in Views/Shared/EditorTemplates).

It likely the editor template that is getting loaded for string does not like a null string being passed.

If you don't have a custom editor template for string (and all you want is a basic textbox), then there is no reason to use EditorFor.