DisplayForModel not rendering my iList(of string)

Question

I have a model, which has a few regular properties like strings and integers, and it also have 2 ilist(of string) properties.

I made a DisplayTemplate for these that looks like this and is called ListOfString.vbhtml:

@ModelType List(Of String)
@If Model IsNot nothing And Model.Any Then
    @<ul> 
        @For i As Integer = 0 To Model.Count
            @<li>@Html.Raw(Model(i))</li> 
        Next
    </ul> 
end if

This is how the properties are decorated:

<UIHint("ListOfString")>
<Display(Name:="Options", ResourceType:=GetType(WebText))>
Public Property Options As List(Of String) = New List(Of String)

Then, in my view, I am calling @Html.DisplayForModel(). Expecting all my properties to be written out by the default Display templates, and my custom one for the lists for the properties that are lists.

All the properties that are not IList(of string) are rendered out fine (it's ugly, but that is a separate problem all together).

I tried having the Display Template in the Views/Shared/DisplayTemplates folder in the project base, and in the Area/Views/controllername/DisplayTemplates folder and neither work.

The lists DO have values in them, and the templates are not being rendered because I put plain "hello" in them and it did not show up. So it isn't a case of model binding going wrong.

Am I completely off my rocker in expecting this to work? I was under the impression that this was one of the great things about display templates and whatnot.

either, or, doesn't work either way. Ideally they would be `Ilist()` but if i can get it working with just `List` I would be ok with that. — Patricia, Oct 19 '13 at 16:37
the result is everything but the lists. if i put plain text, it doesn't render that text either. — Patricia, Oct 22 '13 at 17:23

Denis Borovnev · Answer 1 · 2013-10-21T21:17:46.753

2

It doesn't work because mvc has default display template for Object which renders only simple properties of model (like string, int and etc). You can override this template by adding partial view with name Object.xxx and model type Object to DisplayTemplates folder. You can look example of this template here https://github.com/BrandyFx/ProjectTemplate/blob/master/src/Web/Views/Shared/DisplayTemplates/Object.cshtml

Also you can find default implementation here https://github.com/githubmickey/ASP.NET-Web-Stack/blob/master/src/System.Web.Mvc/Html/DefaultDisplayTemplates.cs - internal static string ObjectTemplate

edited Oct 21 '13 at 21:17

answered Oct 21 '13 at 21:07

Denis Borovnev

486
3
3

ah, i suppose that makes sense. pretty disappointing that it doesn't have it built it to handle properties that are attributed out to say what to use to display them! care to give a run down on what on earth that template is doing? – Patricia Oct 22 '13 at 17:30

score 1 · Accepted Answer · answered Oct 25 '13 at 15:01

I converted this C# Object Display Template linked by Denis to Visual Basic. Like the default object view template, it has a TemplateDepth check, but it's set to 5 instead of 1, and unlike the default, it displays views when metadata.IsComplexType is true.

@Code
    Dim shouldKnow As Func(Of ModelMetadata, Boolean) =
        Function(metadata) metadata.ShowForDisplay And Not ViewData.TemplateInfo.Visited(metadata)
End Code

@If ViewData.TemplateInfo.TemplateDepth > 5 Then
    If Model = Nothing Then
        @ViewData.ModelMetadata.NullDisplayText
    Else
        @ViewData.ModelMetadata.SimpleDisplayText
    End If
Else
    For Each prop In ViewData.ModelMetadata.Properties.Where(shouldKnow)
        If prop.HideSurroundingHtml Then
            @Html.Display(prop.PropertyName)
        Else
            @<div class="control-group">
                @Code
                    Dim label = Html.Label(prop.PropertyName)
                    If String.IsNullOrEmpty(label.ToHtmlString()) = False Then
                    @<div class="control-label">
                        @label
                    </div>
                    End If
                End Code
                <div class="controls">
                    @Html.Display(prop.PropertyName)
                </div>
            </div>
        End If
    Next
End If

score 0 · Answer 3 · answered Oct 23 '13 at 14:25

You can still display each property separately in your view (or a DisplayTemplate dedicated to your view model) :

@Html.DisplayFor(model => model.Options)

This will use ListOfString.

Default DisplayTemplate for Object does not render complex type properties, so if you want to use @Html.DisplayForModel, you'll have to define a DisplayTemplate for your view model, including all your properties separately :

@ModelType MyCustomViewModel
@Html.DisplayFor(model => model.MyStringProp)<br />
@Html.DisplayFor(model => model.MyIntProp)<br />
@Html.DisplayFor(model => model.Options)

If you have a lot of properties, you can go with some more generic solution like in Denis' links.

Thanks for the answer. I know I can do it if i manually write out each property, but I am trying to avoid that. — Patricia, Oct 23 '13 at 14:40

DisplayForModel not rendering my iList(of string)

3 Answers3