MVC3 Strongly typed partial view model binding

Question

I have a strongly typed view, Edit, with a model named OrderModel. In this view, I am using a strongly typed partial view that has a model named OrderTypeModel. The partial view, _OrderTypeAutoComplete, that contains a jqueryui autocomplete textbox. If I render the view with this code,

public ActionResult Edit(){
    return View();
}

My Edit view contains the following Razor markup

<div class="editor-field">
    @Html.Partial("_OrderTypeAutoComplete")
    @Html.HiddenFor(model => model.OrderTypeID)
    @Html.ValidationMessageFor(m => m.OrderTypeID)
</div>

My Partial view contains this razor markup

@{
    Layout = null;
}
<script src="@Url.Content("~/Scripts/jquery-ui-1.8.11.min.js")" type="text/javascript"></script>
@Html.AutoCompleteFor(model => model.OrderTypeID, x =>  x.OrderType, "Items","Orders")

When I render this, all is great and my autocomplete works great (using an auto-complete extension). Anyway, I needed to initialize something in my initial OrderModel, so I changed the code in my controller to this.

public ActionResult Edit(){
    return View(OrderService.GetInitializedOrderModel()); //returns a new OrderModel
}

Now when I render the view, I get the exception: The model item passed into the dictionary is of type 'Testing.Models.OrderModel', but this dictionary requires a model item of type 'Testing.Models.OrderTypeModel'.

on this line in my view @Html.Partial("_OrderTypeAutoComplete")

It seems the Razor engine will create the OrderModel for the view and the OrderTypeModel for the partial view fine when I haven't supplied the OrderModel. This will give the same results.

public ActionResult Edit(){
    return View(new OrderModel())
}

I'm new to MVC so I'm not sure what's going on here. I'm simply trying to provide some simple dropdown values for my view in the OrderModel model that are small enough that I don't require a jquery postback to get. That's the values I'm initialing in my model for the Http Get on my Edit action.

Any help would be appreciated. Thanks.

does your @Html.Partial("_OrderTypeAutoComplete") work properly? because you do not pass data but implement it on partial. how? — Nuri YILMAZ
It does work, but only when I don't pass the view a model to start. It seems Razor will create models for the View and the Partial view. If I supply a model to the view, it then bombs on the Partial. So, if I post back and their is a validation error on post back, it fails then as well when the page refreshes. — Jeff Reddy
Can you add the code for your model classes (OrderModel and OrderTypeModel)? — Jess Chadwick

Jess Chadwick Jess Chadwick · Accepted Answer · 2011-09-22T16:32:52

The class definitions for your model classes are missing from the example so I can't tell exactly what is going on, but...

The @Html.Partial() method has a few overloads:

@Html.Partial(string)
@Html.Partial(string, Object)
@Html.Partial(string, ViewDataDictionary)
@Html.Partial(string, Object, ViewDataDictionary)

The first three overloads are all just "aliases" for the last one - when all's said and done it is the last one that gets called.

When you call the @Html.Partial(string) and do not pass a model value or ViewDataDictionary, ASP.NET MVC will just pass in the ViewDataDictionary for the current view (i.e. this.ViewData).

I other words, a call to:

@Html.Partial(string)

Is essentially equivalent to:

@Html.Partial(string, this.ViewData)

... and in your case, this.ViewData is of type OrderModel, not OrderModelType.

MVC3 Strongly typed partial view model binding

1 Answers