Can I have a named display template for a collection

Question

I have a display for a collection of "SomeObject"

public List<SomeObject> SomeObjects

@Html.DisplayFor(m => m.SomeObjects)

This all works fine.. Then I had a requirement that meant I would need a second different display template for the same collection..

@Html.DisplayFor(m => m.SomeObjects, "NameOfTemplate")

I get the below message when I do this.. I have used named display templates before, but maybe it only works for primitive types - strings etc?

'System.Collections.Generic.List1[SomeObject]', but this dictionary requires a model item of type 'SomeObject'.

Adding code as request

"Test" DisplayTemplate

@model ViewModels.SomeObject

<p class="Namme">
    <span>@Model.Name</span>
</p>

SimpleViewModel

 public class SomeObject
    {
        public string Name { get; set; }
    }

Property in ParentViewModel

public List<SomeObject> SomeObjects { get; set; }

Cshtml file..

@Html.DisplayFor(m => m.SomeObjects, "Test")

To me its a simple question, can a named template be used with a collection or not? Is it another limitation of mvc..

Cheers, John

Make sure the model in the Display template is of the same type your passing in via the DisplayFor razor extension. Seems like it isnt a generic list in your Display Template. For example in your template: '@model IList' opposed to '@model SomeObject' — gdp, Nov 13 '13 at 14:26
I tried what you suggested and it didn't work. My understanding is that model for the displayTemplates should be the single and not the collection.. Here is what I tried and the error @model IList HttpCompileException was unhandled by user code. "External component has thrown an exception." — John, Nov 13 '13 at 14:42
Can you post full code, including the Template. Basically whatever you are passing through via the Display For, that should be the model type for the Display Template. Try putting a '@Html.DisplayFor(m => m .SomeObjects.First(), "TemplateName")'. Seems like your just passing in the incorrect model type. Include the model code for the calling CSHTML page too. — gdp, Nov 13 '13 at 14:46

score 2 · Answer 1 · answered Nov 13 '13 at 15:07

2

Yes you are passing a list of SomeObject to your display template, when it is expecting:

@model ViewModels.SomeObject

You either need to change the template to something like this and accept a list as the view model:

@model IList<ViewModels.SomeObject>

@foreach (var item in Model) {
<p class="Namme">
    <span>@item</span>
</p>
}

Or change what you are passing into the Display Template in the parent CSHTML file and make it a single object of SomeObject something like this:

public List<SomeObject> SomeObjects

@foreach (var item in Model.SomeObjects) {
    Html.DisplayFor(item, "TemplateName")
}

Its hard to answer because im not sure what your trying to achieve, and what SomeObject is, but this should point you in the right direction.

answered Nov 13 '13 at 15:07

gdp

Thanks gdp.. Its a limitation of mvc so.. As passing the list(when not a named display template works fine, mvc does the looping for me) Once you use a named template, it will pass the collection, so yes the model will need to be the collection, hence needing the for loop within. Pointless to me so, as I had a for loop in my calling code, I was wanting to use the display template so that I could eliminate it. As mentions once Its not a named template it works fine.. ah well. live and learn :) – John Nov 13 '13 at 15:11
Its just that you had the incorrect model type in your custom Display Template. Changing this to a list in the template is what MVC will be doing anyway under the hood by solely using this: '@Html.DisplayFor(m => m.MyCollection)'. – gdp Nov 13 '13 at 15:14
true, but inside my template if I try and access the elements of the object I need the for loop.. what I wanted to avoid.. when its not a named template i dont need a loop. thats the main difference for me.. – John Nov 13 '13 at 15:16
2

Yeh you cant avoid that unfortunately, if you want more granular control then you have to loop the model. – gdp Nov 13 '13 at 15:17

score 0 · Answer 2 · answered Nov 13 '13 at 15:02

0

The type of SomObjects is List<SomeObjects> so the view template must have a matching model:

@model `ICollection<ViewModels.SomeObject>`

I prefer to not restrict the view to the concrete List<> class but rather use an interface.

That also means that you have to adjust your template to use a loop to iterate through the items in the collection.

answered Nov 13 '13 at 15:02

Anders Abel

Anders, If I do that, I would need to iterate over it with a for loop. The point of me using the template was to remove the for loop from the calling page.. By putting the single Object as the model I dont need the loop and mvc takes care of the iterating.. This all works fine, until I try a named template which is what my question is about, as I have got many working with collections.. Related to this post.. http://stackoverflow.com/questions/8002059/asp-net-mvc-display-template-for-a-collection – John Nov 13 '13 at 15:07
1

The problem is that you can only tell MVC what template to use for the *entire collection* then it uses its internal logic to find the template for each item. If that is what you want to control you're probably out of luck as I don't know of a way to pass a display template to that second lookup step. – Anders Abel Nov 13 '13 at 15:11

2 Answers2