Best way to pass a model to a new ViewDataDictionary in MVC6

Question

I'm trying to migrate my current MVC5 project over to MVC6 but have hit a minor snag around the new namespaces/methods, primarily with ViewDataDictionary . In MVC5 you could easily initiate a new ViewDataDictionary by just passing your model like so...

PartialViewResult pv = new PartialViewResult();
pv.ViewData = new ViewDataDictionary(model);

...but there doesn't seem to be any overloads for this in MVC6 without actually having a ViewDataDictionary object available.

So I suppose my question is, what is the best method to create a new ViewDataDictionary from scratch? I can see the following overload but I'm unable to find any examples on how to use it.

public ViewDataDictionary(IModelMetadataProvider metadataProvider, ModelStateDictionary modelState);

Answer 1

You could create a new ViewDataDictionary and then assign its model property.

• The new framework does that, the ViewDataDictionaryControllerPropertyActivator creates the ViewData. The model model property is set when you use one of the helper methods in the Controller like View , as in return View(model)

You will just need to get an IModelMetadataProvider which you can either get using DI in your controller or via the HttpContext.ApplicationServices service locator.

public IActionResult SomeAction()
{
    var modelMetadataProvider = this.Context.ApplicationServices.GetRequiredService<IModelMetadataProvider>();
    var viewDataDictionary = new ViewDataDictionary<FooModel>(modelMetadataProvider, new ModelStateDictionary());
    viewDataDictionary.Model = new FooModel();

    ...        

}

Maybe you could provide an extension method:

public static ViewDataDictionary<T> CreateViewDataDictionary<T>(this HttpContext httpContext, T model)
{
    var modelMetadataProvider = httpContext.ApplicationServices.GetRequiredService<IModelMetadataProvider>();
    return new ViewDataDictionary<T>(modelMetadataProvider, new ModelStateDictionary())
    {
        Model = model
    };
}

public IActionResult SomeAction()
{
    var viewDataDictionary = this.Context.CreateViewDataDictionary(new FooModel());

    ...

}