Pass Additional ViewData to DisplayFor Template

Question

I want to pass an object Model.AvailableVerticalType along with the expression and templateName in the call to the HTML Helper DisplayFor. Without passing the object, the DisplayFor() syntax looks like this:

@Html.DisplayFor(o => offer, MVC.Shared.Views.DisplayTemplates.OfferDetail)

The OfferDetail template accepts an object of the type Offer only:

@model DGS.DGSAPI.UI.BusinessModels.Offer

So I need a way to send the AvailableVerticleType through the ViewData. Is it possible? What would be the syntax for passing ViewData in DisplayFor()?

Is the object part of your model, or have you added in using `ViewBag` of `ViewData` in the GET method? Note that its [this overload](https://msdn.microsoft.com/en-us/library/system.web.mvc.html.displayextensions.displayfor(v=vs.118).aspx#M:System.Web.Mvc.Html.DisplayExtensions.DisplayFor``2%28System.Web.Mvc.HtmlHelper{``0},System.Linq.Expressions.Expression{System.Func{``0,``1}},System.String,System.Object%29) that you want — , Jun 10 '16 at 07:13
To pass it you would use `@Html.DisplayFor(o => offer, MVC.Shared.Views.DisplayTemplates.OfferDetail, new { data = Model.AvailableVerticalType } )` and then in the template you can access it using `(yourType)ViewData["data"]` — , Jun 10 '16 at 07:18
@StephenMuecke, if that's the answer, please post it as an answer. — Kevin, Apr 26 '18 at 14:44

score 6 · Answer 1 · answered Mar 27 '20 at 17:21

As suggested by user3559349, you can pass an anonymous object into the DisplayFor() method and that get's to be a part of the ViewData dictionary.

In your view:

@Html.DisplayFor(o => offer, "OfferDetail", new {AvailableVerticalType = Model.AvailableVerticalType }

In your OfferDetail template:

(AvailableVerticalType)ViewData["AvailableVerticalType"]

You could also just create a partial view that has a model declared for the AvailableVerticalType and reference that in your main view.

@model AvailableVerticalType

Hooman Bahreini · Answer 2 · 2020-06-28T01:01:44.613

You pass it in ViewDataDictionary, example below:

// optional: if you don't want to use "AdditionalData" magic string
public static class ViewDataKeys
{
    public const string AdditionalData = "AdditionalData";
}

We can use the 2nd overload of DisplayFor and pass the additional data in ViewDataDictionary:

@Html.DisplayFor(m => m.MyModel, new ViewDataDictionary { { ViewDataKeys.AdditionalData, "additional-value" } })

And in your DisplayFor template you can access the ViewDataDictionary like this:

@{
    string additionalData = ViewData[ViewDataKeys.AdditionalData];

    /*
     * if you need to cast the data type:
     * var additionalData = (AdditionalDataType)ViewData[ViewDataKeys.AdditionalData];
     */
}

You can also pass multiple additional data, for example:

@Html.DisplayFor(m => m.MyModel, new ViewDataDictionary { 
    { ViewDataKeys.AdditionalData1, "additional-value1" },
    { ViewDataKeys.AdditionalData2, "additional-value2" }
})

Keeping in mind that it is always better to pass the data in a Model.

To me, this is a bit of an XY problem, which the last line of your question really gets to the heart of. The OP is asking about the `ViewData` because they don't know _how_ to pass the data as part of their _model_. Given that, is there a way to extend the model while still relying the expression bindings necessary for the `DisplayFor()` template to properly assess e.g. validation attributes on the original target property? (I'm not certain there is, which thus necessitates the use of `ViewData`.) — Jeremy Caney, Jun 27 '20 at 21:06

Pass Additional ViewData to DisplayFor Template

2 Answers2