ArgumentNullException with ForeignKey in EditorTemplates

[Sébastien]

I use that:
    @(Html.Kendo().Grid<Lorem.Core.DataModels.Contacts.DMConEmail>()
    .Name("ContactEmails")
    .Columns(columns =>
    {
        columns.ForeignKey(p => p.Type, Html.GetEnumList(typeof(Lorem.Core.DataModels.Contacts.DMConEmailType)));
        columns.Bound(p => p.Email);
        columns.Command(command => { command.Edit(); command.Destroy(); });
    })
    .ToolBar(toolbar => toolbar.Create())
    .Editable(editable => editable.Mode(GridEditMode.InLine))
    .DataSource(datasource => datasource.Ajax()
        .Model(model => model.Id(p => p.IdEmail))
        .Create(update => update.Action("EmailInsert", "Contact", new { idContact = Model.IdContact }))
        .Read(read => read.Action("EmailGetList", "Contact", new { idContact = Model.IdContact }))
        .Update(update => update.Action("EmailUpdate", "Contact"))
        .Destroy(update => update.Action("EmailDelete", "Contact"))
        ))

And I have a column that use an Enum to choose the email type. When I use that in a view, all is working fine. When I use it in an EditorTemplates I have this exception:
Ligne 1 : @model object
Ligne 2 :
Ligne 3 : @(
Ligne 4 : Html.Kendo().DropDownListFor(m => m)
Ligne 5 : .BindTo((SelectList)ViewData[ViewData.TemplateInfo.GetFullHtmlFieldName("") + "_Data"])

[ArgumentNullException: La valeur ne peut pas être null.
Nom du paramètre : source]
System.Linq.Enumerable.Select(IEnumerable`1 source, Func`2 selector) +4090943
Kendo.Mvc.UI.Fluent.DropDownListBuilder.BindTo(IEnumerable`1 dataSource) +88
ASP._Page_Views_Shared_EditorTemplates_GridForeignKey_cshtml.Execute() in c:\DCM\SVNPortailDCM\trunk\Softwares\Lorem\MVC\Views\Shared\EditorTemplates\GridForeignKey.cshtml:3
System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +198
System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +104
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +90
System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +235

[Sébastien]

The GetEnumList function:

        public static SelectList GetEnumList(this HtmlHelper htmlHelper, Type type)
        {
            List<SelectListItem> result = new List<SelectListItem>();
            foreach(Enum value in (Enum.GetValues(type))) {
                result.Add(new SelectListItem() { Value = Convert.ToInt32(value).ToString(), Text = AttributeUtil.GetDisplayName(value) });
            }
            return new SelectList(result, "Value", "Text");
        }

[Sébastien]

The exception don't seem to come from EditorTemplates, but come from a model property containing another model class used by the child EditorTemplate. The class hierarchy don't seem to work like another Microsoft MVC Controls.

[Daniel]

Hello,

The exception would be thrown by the dropdownlist if there is a prefix for the editor template because the ViewData key will not be correct and null will be passed to the BindTo method. You should clear the prefix before rendering the grid and restore it after if needed:

@{
    var prefix = ViewData.TemplateInfo.HtmlFieldPrefix;
    ViewData.TemplateInfo.HtmlFieldPrefix = string.Empty;
}

@(Html.Kendo().Grid<Lorem.Core.DataModels.Contacts.DMConEmail>()
    .Name("ContactEmails")
    ...
)

@{
    ViewData.TemplateInfo.HtmlFieldPrefix = prefix;
}

in order to avoid the exception and avoid the editors to be generated with a name that is incorrect in the context of the grid editing:


Regards,
Daniel
Telerik

 

 

[Sébastien]

If I clear the prefix, the ViewModel was all null, so I can't clear the prefix.

[Daniel]

Hello again,

Could you provide a runnable sample that demonstrates the issue when clearing the prefix?

Regards,
Daniel
Telerik