ASP MVC 5.2 using nested dictionaries for htmlAttributes in EditorFor

Question

I want to pass a nested Dictionary into the EditorFor viewData.

@{
    var viewData = new RouteValueDictionary();
    var htmlAttributes = new RouteValueDictionary();
    htmlAttributes.Add("title", "foo");
    viewData["htmlAttributes"] = htmlAttributes;
}
Html.EditorFor(model => model.SomeProperty, viewData);

The problem is that the tile="foo" does not get rendered. When I'm using

var htmlAttributes = new {title = "foo"};

everything is working as expected.

I need htmlAttributes to be a Dictionary, because in my application it is dynamically generated.

So how can I pass a Dictionary in there. I already tried to pass in thmlAttributes as an ExpandoObject, but that does not work either.

Answer 1

It is currently not possible (MVC 5.2) see this Bug: https://aspnetwebstack.codeplex.com/workitem/1736

Answer 2

I am afraid it not possible to do, at least not the easy way cuz the EditorFor creates many html elements and therefor it's not clear on which element the htmlAttributes should apply.

However, the hard way is to implement your own Object.cshtml in Views/Shared/EditorTemplates/Object.cshtml. Following is an example of custom Object.cshtml (bootstrap specific) where you can grab values from ViewData and construct the output Html anyway you like.

@using MvcApplication1.Utility
@if (ViewData.TemplateInfo.TemplateDepth > 1) {
    @ViewData.ModelMetadata.SimpleDisplayText
} else {
    foreach (var prop in ViewData.ModelMetadata.Properties.Where(pm => pm.ShowForDisplay && !ViewData.TemplateInfo.Visited(pm))) {
        var htmlString = prop.IsReadOnly ? Html.Display(prop.PropertyName) : Html.Editor(prop.PropertyName);
        if (prop.HideSurroundingHtml) {
            @htmlString
        }
        else
        {
            var errors = Html.ValidationErrors(prop);
            <div class="form-group @(prop.IsReadOnly ? "form-group-readonly" : "") @(errors.Any() ? "has-error has-feedback" : "")">
                <label class="control-label" for="@ViewData.TemplateInfo.GetFullHtmlFieldId(prop.PropertyName)">@prop.GetDisplayName()</label>
                @htmlString
                @foreach (var err in errors)
                {
                    <div class="field-validation-error">@err.ErrorMessage</div>
                }
            </div>
        }
    }
}

and the utility functions

    public static IEnumerable<ModelError> ValidationErrors<TModel>(this HtmlHelper<TModel> htmlHelper, ModelMetadata modelMetadata)
    {
        string modelName = htmlHelper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(modelMetadata.PropertyName);
        return ValidationErrors(htmlHelper, modelName);
    }

    public static IEnumerable<ModelError> ValidationErrors<TModel>(this HtmlHelper<TModel> htmlHelper)
    {
        return ValidationErrors(htmlHelper, String.Empty);
    }

    private static IEnumerable<ModelError> ValidationErrors(this HtmlHelper htmlHelper, String modelName)
    {
        FormContext formContext = htmlHelper.ViewContext.FormContext;
        if (formContext == null)
            yield break;

        if (!htmlHelper.ViewData.ModelState.ContainsKey(modelName))
            yield break;

        ModelState modelState = htmlHelper.ViewData.ModelState[modelName];
        if (modelState == null)
            yield break;

        ModelErrorCollection modelErrors = modelState.Errors;
        if (modelErrors == null)
            yield break;

        foreach(var err in modelErrors)
            yield return err;
    }